diff --git a/lib/Activity/Provider/Base.php b/lib/Activity/Provider/Base.php
index f1cc6c499e5..0bb75b57c1b 100644
--- a/lib/Activity/Provider/Base.php
+++ b/lib/Activity/Provider/Base.php
@@ -43,9 +43,6 @@ abstract class Base implements IProvider {
 	protected IUserManager $userManager;
 	protected Manager $manager;
 
-	/** @var string[] */
-	protected array $displayNames = [];
-
 	public function __construct(IFactory $languageFactory,
 								IURLGenerator $url,
 								Config $config,
@@ -134,22 +131,10 @@ protected function getFormerRoom(IL10N $l, int $roomId): array {
 	}
 
 	protected function getUser(string $uid): array {
-		if (!isset($this->displayNames[$uid])) {
-			$this->displayNames[$uid] = $this->getDisplayName($uid);
-		}
-
 		return [
 			'type' => 'user',
 			'id' => $uid,
-			'name' => $this->displayNames[$uid],
+			'name' => $this->userManager->getDisplayName($uid) ?? $uid,
 		];
 	}
-
-	protected function getDisplayName(string $uid): string {
-		$user = $this->userManager->get($uid);
-		if ($user instanceof IUser) {
-			return $user->getDisplayName();
-		}
-		return $uid;
-	}
 }
diff --git a/lib/Chat/AutoComplete/SearchPlugin.php b/lib/Chat/AutoComplete/SearchPlugin.php
index 9cabe3e853b..1ca840db782 100644
--- a/lib/Chat/AutoComplete/SearchPlugin.php
+++ b/lib/Chat/AutoComplete/SearchPlugin.php
@@ -33,7 +33,6 @@
 use OCP\Collaboration\Collaborators\ISearchResult;
 use OCP\Collaboration\Collaborators\SearchResultType;
 use OCP\IL10N;
-use OCP\IUser;
 use OCP\IUserManager;
 
 class SearchPlugin implements ISearchPlugin {
@@ -139,18 +138,18 @@ protected function searchUsers(string $search, array $userIds, ISearchResult $se
 				continue;
 			}
 
-			$user = $this->userManager->get($userId);
-			if (!$user instanceof IUser) {
+			$userDisplayName = $this->userManager->getDisplayName($userId);
+			if ($userDisplayName === null) {
 				continue;
 			}
 
-			if (strtolower($user->getDisplayName()) === $search) {
-				$exactMatches[] = $this->createResult('user', $user->getUID(), $user->getDisplayName());
+			if (strtolower($userDisplayName) === $search) {
+				$exactMatches[] = $this->createResult('user', $userId, $userDisplayName);
 				continue;
 			}
 
-			if (stripos($user->getDisplayName(), $search) !== false) {
-				$matches[] = $this->createResult('user', $user->getUID(), $user->getDisplayName());
+			if (stripos($userDisplayName, $search) !== false) {
+				$matches[] = $this->createResult('user', $userId, $userDisplayName);
 				continue;
 			}
 		}
@@ -207,12 +206,7 @@ protected function searchGuests(string $search, array $attendees, ISearchResult
 
 	protected function createResult(string $type, string $uid, string $name): array {
 		if ($type === 'user' && $name === '') {
-			$user = $this->userManager->get($uid);
-			if ($user instanceof IUser) {
-				$name = $user->getDisplayName();
-			} else {
-				$name = $uid;
-			}
+			$name = $this->userManager->getDisplayName($uid) ?? $uid;
 		}
 
 		return [
diff --git a/lib/Chat/Notifier.php b/lib/Chat/Notifier.php
index 5874d05bf0f..3f048c05668 100644
--- a/lib/Chat/Notifier.php
+++ b/lib/Chat/Notifier.php
@@ -467,11 +467,11 @@ protected function shouldMentionedUserBeNotified(string $userId, IComment $comme
 				// so they can see the room in their room list and
 				// the notification can be parsed and links to an existing room,
 				// where they are a participant of.
-				$user = $this->userManager->get($userId);
+				$userDisplayName = $this->userManager->getDisplayName($userId);
 				$this->participantService->addUsers($room, [[
 					'actorType' => Attendee::ACTOR_USERS,
 					'actorId' => $userId,
-					'displayName' => $user ? $user->getDisplayName() : $userId,
+					'displayName' => $userDisplayName ?? $userId,
 				]]);
 				return true;
 			}
diff --git a/lib/Chat/Parser/UserMention.php b/lib/Chat/Parser/UserMention.php
index 531dbd037da..4c4ba060e0b 100644
--- a/lib/Chat/Parser/UserMention.php
+++ b/lib/Chat/Parser/UserMention.php
@@ -31,7 +31,6 @@
 use OCA\Talk\Room;
 use OCP\Comments\ICommentsManager;
 use OCP\IL10N;
-use OCP\IUser;
 use OCP\IUserManager;
 
 /**
@@ -91,8 +90,8 @@ public function parseMessage(Message $chatMessage): void {
 			}
 
 			if ($mention['type'] === 'user') {
-				$user = $this->userManager->get($mention['id']);
-				if (!$user instanceof IUser) {
+				$userDisplayName = $this->userManager->getDisplayName($mention['id']);
+				if ($userDisplayName === null) {
 					continue;
 				}
 			}
diff --git a/lib/Controller/CallController.php b/lib/Controller/CallController.php
index f55b62bc73a..5be4ae1485b 100644
--- a/lib/Controller/CallController.php
+++ b/lib/Controller/CallController.php
@@ -36,7 +36,6 @@
 use OCP\AppFramework\Http\DataResponse;
 use OCP\AppFramework\Utility\ITimeFactory;
 use OCP\IRequest;
-use OCP\IUser;
 use OCP\IUserManager;
 
 class CallController extends AEnvironmentAwareController {
@@ -78,9 +77,9 @@ public function getPeersForCall(): DataResponse {
 				if ($participant->getAttendee()->getDisplayName()) {
 					$displayName = $participant->getAttendee()->getDisplayName();
 				} else {
-					$user = $this->userManager->get($participant->getAttendee()->getActorId());
-					if ($user instanceof IUser) {
-						$displayName = $user->getDisplayName();
+					$userDisplayName = $this->userManager->getDisplayName($participant->getAttendee()->getActorId());
+					if ($userDisplayName !== null) {
+						$displayName = $userDisplayName;
 					}
 				}
 			} else {
diff --git a/lib/Controller/RoomController.php b/lib/Controller/RoomController.php
index 49e2e7a89fb..9f3e0fc85fd 100644
--- a/lib/Controller/RoomController.php
+++ b/lib/Controller/RoomController.php
@@ -1011,11 +1011,11 @@ public function getParticipants(bool $includeStatus = false): DataResponse {
 
 				$result['displayName'] = $participant->getAttendee()->getDisplayName();
 				if (!$result['displayName']) {
-					$user = $this->userManager->get($userId);
-					if (!$user instanceof IUser) {
+					$userDisplayName = $this->userManager->getDisplayName($userId);
+					if ($userDisplayName === null) {
 						continue;
 					}
-					$result['displayName'] = $user->getDisplayName();
+					$result['displayName'] = $userDisplayName;
 				}
 
 				if (isset($statuses[$userId])) {
diff --git a/lib/Manager.php b/lib/Manager.php
index f72fc5c5b1b..1e2798ee04d 100644
--- a/lib/Manager.php
+++ b/lib/Manager.php
@@ -1002,8 +1002,8 @@ public function resolveRoomDisplayName(Room $room, string $userId): string {
 			}
 
 			if ($otherParticipant === '' && $room->getName() !== '') {
-				$user = $this->userManager->get($room->getName());
-				$otherParticipant = $user instanceof IUser ? $user->getDisplayName() : $this->l->t('Deleted user (%s)', $room->getName());
+				$userDisplayName = $this->userManager->getDisplayName($room->getName());
+				$otherParticipant = $userDisplayName ?? $this->l->t('Deleted user (%s)', $room->getName());
 			}
 
 			return $otherParticipant;
@@ -1054,8 +1054,7 @@ protected function getRoomNameByParticipants(Room $room): string {
 		$displayNames = [];
 
 		foreach ($users as $participantId) {
-			$user = $this->userManager->get($participantId);
-			$displayNames[] = $user instanceof IUser ? $user->getDisplayName() : $participantId;
+			$displayNames[] = $this->userManager->getDisplayName($participantId) ?? $participantId;
 		}
 
 		$roomName = implode(', ', $displayNames);
diff --git a/lib/Notification/Notifier.php b/lib/Notification/Notifier.php
index 68af3211324..77dbcfaf537 100644
--- a/lib/Notification/Notifier.php
+++ b/lib/Notification/Notifier.php
@@ -332,13 +332,13 @@ protected function parseChatMessage(INotification $notification, Room $room, Par
 		$isGuest = false;
 		if ($subjectParameters['userType'] === 'users') {
 			$userId = $subjectParameters['userId'];
-			$user = $this->userManager->get($userId);
+			$userDisplayName = $this->userManager->getDisplayName($userId);
 
-			if ($user instanceof IUser) {
+			if ($userDisplayName !== null) {
 				$richSubjectUser = [
 					'type' => 'user',
 					'id' => $userId,
-					'name' => $user->getDisplayName(),
+					'name' => $userDisplayName,
 				];
 			}
 		} else {
@@ -559,8 +559,8 @@ protected function parseInvitation(INotification $notification, Room $room, IL10
 		$parameters = $notification->getSubjectParameters();
 		$uid = $parameters['actorId'] ?? $parameters[0];
 
-		$user = $this->userManager->get($uid);
-		if (!$user instanceof IUser) {
+		$userDisplayName = $this->userManager->getDisplayName($uid);
+		if ($userDisplayName === null) {
 			throw new AlreadyProcessedException();
 		}
 
@@ -574,13 +574,13 @@ protected function parseInvitation(INotification $notification, Room $room, IL10
 			}
 
 			$notification
-				->setParsedSubject(str_replace('{user}', $user->getDisplayName(), $subject))
+				->setParsedSubject(str_replace('{user}', $userDisplayName, $subject))
 				->setRichSubject(
 					$subject, [
 						'user' => [
 							'type' => 'user',
 							'id' => $uid,
-							'name' => $user->getDisplayName(),
+							'name' => $userDisplayName,
 						],
 						'call' => [
 							'type' => 'call',
@@ -599,13 +599,13 @@ protected function parseInvitation(INotification $notification, Room $room, IL10
 			}
 
 			$notification
-				->setParsedSubject(str_replace(['{user}', '{call}'], [$user->getDisplayName(), $roomName], $subject))
+				->setParsedSubject(str_replace(['{user}', '{call}'], [$userDisplayName, $roomName], $subject))
 				->setRichSubject(
 					$subject, [
 						'user' => [
 							'type' => 'user',
 							'id' => $uid,
-							'name' => $user->getDisplayName(),
+							'name' => $userDisplayName,
 						],
 						'call' => [
 							'type' => 'call',
@@ -639,8 +639,8 @@ protected function parseCall(INotification $notification, Room $room, IL10N $l):
 		if ($room->getType() === Room::TYPE_ONE_TO_ONE) {
 			$parameters = $notification->getSubjectParameters();
 			$calleeId = $parameters['callee'];
-			$user = $this->userManager->get($calleeId);
-			if ($user instanceof IUser) {
+			$userDisplayName = $this->userManager->getDisplayName($calleeId);
+			if ($userDisplayName !== null) {
 				if ($this->notificationManager->isPreparingPushNotification() || $this->participantService->hasActiveSessionsInCall($room)) {
 					$notification = $this->addActionButton($notification, $l->t('Answer call'));
 					$subject = $l->t('{user} would like to talk with you');
@@ -650,13 +650,13 @@ protected function parseCall(INotification $notification, Room $room, IL10N $l):
 				}
 
 				$notification
-					->setParsedSubject(str_replace('{user}', $user->getDisplayName(), $subject))
+					->setParsedSubject(str_replace('{user}', $userDisplayName, $subject))
 					->setRichSubject(
 						$subject, [
 							'user' => [
 								'type' => 'user',
 								'id' => $calleeId,
-								'name' => $user->getDisplayName(),
+								'name' => $userDisplayName,
 							],
 							'call' => [
 								'type' => 'call',
diff --git a/lib/Service/ParticipantService.php b/lib/Service/ParticipantService.php
index 852e33d7f84..9742c280579 100644
--- a/lib/Service/ParticipantService.php
+++ b/lib/Service/ParticipantService.php
@@ -680,12 +680,12 @@ public function ensureOneToOneRoomIsFilled(Room $room): void {
 		$missingUsers = array_diff($users, $participants);
 
 		foreach ($missingUsers as $userId) {
-			$user = $this->userManager->get($userId);
-			if ($user instanceof IUser) {
+			$userDisplayName = $this->userManager->getDisplayName($userId);
+			if ($userDisplayName !== null) {
 				$this->addUsers($room, [[
 					'actorType' => Attendee::ACTOR_USERS,
-					'actorId' => $user->getUID(),
-					'displayName' => $user->getDisplayName(),
+					'actorId' => $userId,
+					'displayName' => $userDisplayName,
 					'participantType' => Participant::OWNER,
 				]]);
 			}
diff --git a/tests/php/Activity/Provider/BaseTest.php b/tests/php/Activity/Provider/BaseTest.php
index 7a598279ad5..9fc2bc7dcd1 100644
--- a/tests/php/Activity/Provider/BaseTest.php
+++ b/tests/php/Activity/Provider/BaseTest.php
@@ -254,44 +254,7 @@ public function testGetRoom($type, $id, $name, $expectedName, $expectedType) {
 		], self::invokePrivate($provider, 'getRoom', [$room, 'user']));
 	}
 
-	public function dataGetUser() {
-		return [
-			['test', [], false, 'Test'],
-			['foo', ['admin' => 'Admin'], false, 'Bar'],
-			['admin', ['admin' => 'Administrator'], true, 'Administrator'],
-		];
-	}
-
-	/**
-	 * @dataProvider dataGetUser
-	 *
-	 * @param string $uid
-	 * @param array $cache
-	 * @param bool $cacheHit
-	 * @param string $name
-	 */
-	public function testGetUser($uid, $cache, $cacheHit, $name) {
-		$provider = $this->getProvider(['getDisplayName']);
-
-		self::invokePrivate($provider, 'displayNames', [$cache]);
-
-		if (!$cacheHit) {
-			$provider->expects($this->once())
-				->method('getDisplayName')
-				->with($uid)
-				->willReturn($name);
-		} else {
-			$provider->expects($this->never())
-				->method('getDisplayName');
-		}
-
-		$result = self::invokePrivate($provider, 'getUser', [$uid]);
-		$this->assertSame('user', $result['type']);
-		$this->assertSame($uid, $result['id']);
-		$this->assertSame($name, $result['name']);
-	}
-
-	public function dataGetDisplayName() {
+	public function dataGetUser(): array {
 		return [
 			['test', true, 'Test'],
 			['foo', false, 'foo'],
@@ -299,31 +262,31 @@ public function dataGetDisplayName() {
 	}
 
 	/**
-	 * @dataProvider dataGetDisplayName
+	 * @dataProvider dataGetUser
 	 *
 	 * @param string $uid
 	 * @param bool $validUser
 	 * @param string $name
 	 */
-	public function testGetDisplayName($uid, $validUser, $name) {
+	public function testGetUser(string $uid, bool $validUser, string $name): void {
 		$provider = $this->getProvider();
 
 		if ($validUser) {
-			$user = $this->createMock(IUser::class);
-			$user->expects($this->once())
-				->method('getDisplayName')
-				->willReturn($name);
 			$this->userManager->expects($this->once())
-				->method('get')
+				->method('getDisplayName')
 				->with($uid)
-				->willReturn($user);
+				->willReturn($name);
 		} else {
 			$this->userManager->expects($this->once())
-				->method('get')
+				->method('getDisplayName')
 				->with($uid)
 				->willReturn(null);
 		}
 
-		$this->assertSame($name, self::invokePrivate($provider, 'getDisplayName', [$uid]));
+		$this->assertSame([
+			'type' => 'user',
+			'id' => $uid,
+			'name' => $name,
+		], self::invokePrivate($provider, 'getUser', [$uid]));
 	}
 }
diff --git a/tests/php/Chat/AutoComplete/SearchPluginTest.php b/tests/php/Chat/AutoComplete/SearchPluginTest.php
index a88a0c60559..d60d1ee8caa 100644
--- a/tests/php/Chat/AutoComplete/SearchPluginTest.php
+++ b/tests/php/Chat/AutoComplete/SearchPluginTest.php
@@ -167,13 +167,13 @@ public function dataSearchUsers() {
 		return [
 			['test', [], [], [], []],
 			['test', ['current', 'foo', 'test', 'test1'], [
-				['uid' => 'current', 'name' => 'test'],
-				['uid' => 'test', 'name' => 'Te st'],
-				['uid' => 'test1', 'name' => 'Te st 1'],
+				['current', 'test'],
+				['test', 'Te st'],
+				['test1', 'Te st 1'],
 			], [['test1' => '']], [['test' => '']]],
 			['test', ['foo', 'bar'], [
-				['uid' => 'foo', 'name' => 'Test'],
-				['uid' => 'bar', 'name' => 'test One'],
+				['foo', 'Test'],
+				['bar', 'test One'],
 			], [['bar' => 'test One']], [['foo' => 'Test']]],
 			['', ['foo', 'bar'], [
 			], [['foo' => ''], ['bar' => '']], []],
@@ -191,13 +191,9 @@ public function dataSearchUsers() {
 	public function testSearchUsers($search, array $userIds, array $userNames, array $expected, array $expectedExact) {
 		$result = $this->createMock(ISearchResult::class);
 
-		$userMap = array_map(function ($userData) {
-			return [$userData['uid'], $this->createUserMock($userData)];
-		}, $userNames);
-
 		$this->userManager->expects($this->any())
-			->method('get')
-			->willReturnMap($userMap);
+			->method('getDisplayName')
+			->willReturnMap($userNames);
 
 		$result->expects($this->once())
 			->method('addResultSet')
@@ -286,12 +282,12 @@ public function dataCreateResult() {
 	public function testCreateResult($type, $uid, $name, $managerName, array $expected) {
 		if ($managerName !== null) {
 			$this->userManager->expects($this->any())
-				->method('get')
+				->method('getDisplayName')
 				->with($uid)
-				->willReturn($this->createUserMock(['uid' => $uid, 'name' => $managerName]));
+				->willReturn($managerName);
 		} else {
 			$this->userManager->expects($this->any())
-				->method('get')
+				->method('getDisplayName')
 				->with($uid)
 				->willReturn(null);
 		}
diff --git a/tests/php/Chat/Parser/UserMentionTest.php b/tests/php/Chat/Parser/UserMentionTest.php
index e72afeed228..9893a947b1a 100644
--- a/tests/php/Chat/Parser/UserMentionTest.php
+++ b/tests/php/Chat/Parser/UserMentionTest.php
@@ -34,7 +34,6 @@
 use OCP\Comments\IComment;
 use OCP\Comments\ICommentsManager;
 use OCP\IL10N;
-use OCP\IUser;
 use OCP\IUserManager;
 use PHPUnit\Framework\MockObject\MockObject;
 use Test\TestCase;
@@ -97,7 +96,7 @@ public function testGetRichMessageWithoutEnrichableReferences() {
 		$this->assertEquals([], $chatMessage->getMessageParameters());
 	}
 
-	public function testGetRichMessageWithSingleMention() {
+	public function testGetRichMessageWithSingleMention(): void {
 		$mentions = [
 			['type' => 'user', 'id' => 'testUser'],
 		];
@@ -109,9 +108,9 @@ public function testGetRichMessageWithSingleMention() {
 			->willReturn('testUser display name');
 
 		$this->userManager->expects($this->once())
-			->method('get')
+			->method('getDisplayName')
 			->with('testUser')
-			->willReturn($this->createMock(IUser::class));
+			->willReturn('testUser display name');
 
 		/** @var Room|MockObject $room */
 		$room = $this->createMock(Room::class);
@@ -148,9 +147,9 @@ public function testGetRichMessageWithDuplicatedMention() {
 			->willReturn('testUser display name');
 
 		$this->userManager->expects($this->once())
-			->method('get')
+			->method('getDisplayName')
 			->with('testUser')
-			->willReturn($this->createMock(IUser::class));
+			->willReturn('testUser display name');
 
 		/** @var Room|MockObject $room */
 		$room = $this->createMock(Room::class);
@@ -210,12 +209,15 @@ public function testGetRichMessageWithMentionsFullyIncludedInOtherMentions(strin
 			});
 
 		$this->userManager->expects($this->exactly(2))
-			->method('get')
+			->method('getDisplayName')
 			->withConsecutive(
 				[$longerId],
 				[$baseId]
 			)
-			->willReturn($this->createMock(IUser::class));
+			->willReturnOnConsecutiveCalls(
+				$longerId . ' display name',
+				$baseId . ' display name'
+			);
 
 		/** @var Room|MockObject $room */
 		$room = $this->createMock(Room::class);
@@ -271,13 +273,17 @@ public function testGetRichMessageWithSeveralMentions() {
 			);
 
 		$this->userManager->expects($this->exactly(3))
-			->method('get')
+			->method('getDisplayName')
 			->withConsecutive(
 				['testUser1'],
 				['testUser2'],
 				['testUser3']
 			)
-			->willReturn($this->createMock(IUser::class));
+			->willReturnOnConsecutiveCalls(
+				'testUser1 display name',
+				'testUser2 display name',
+				'testUser3 display name'
+			);
 
 		/** @var Room|MockObject $room */
 		$room = $this->createMock(Room::class);
@@ -325,10 +331,10 @@ public function testGetRichMessageWithNonExistingUserMention() {
 			->willReturn('testUser display name');
 
 		$this->userManager->expects($this->exactly(2))
-			->method('get')
+			->method('getDisplayName')
 			->willReturnMap([
 				['me', null],
-				['testUser', $this->createMock(IUser::class)],
+				['testUser', 'testUser display name'],
 			]);
 
 		/** @var Room|MockObject $room */
@@ -365,9 +371,9 @@ public function testGetRichMessageWhenDisplayNameCanNotBeResolved() {
 			->willThrowException(new \OutOfBoundsException());
 
 		$this->userManager->expects($this->once())
-			->method('get')
+			->method('getDisplayName')
 			->with('testUser')
-			->willReturn($this->createMock(IUser::class));
+			->willReturn('existing user but does not resolve later');
 
 		/** @var Room|MockObject $room */
 		$room = $this->createMock(Room::class);
diff --git a/tests/php/Notification/NotifierTest.php b/tests/php/Notification/NotifierTest.php
index 2192b3de988..2cf02639cc6 100644
--- a/tests/php/Notification/NotifierTest.php
+++ b/tests/php/Notification/NotifierTest.php
@@ -19,7 +19,7 @@
  *
  */
 
-namespace OCA\Talk\Tests\php\Notifications;
+namespace OCA\Talk\Tests\php\Notification;
 
 use OCA\FederatedFileSharing\AddressHandler;
 use OCA\Talk\Chat\CommentsManager;
@@ -113,7 +113,7 @@ public function setUp(): void {
 		);
 	}
 
-	public function dataPrepareOne2One() {
+	public function dataPrepareOne2One(): array {
 		return [
 			['admin', 'Admin', 'Admin invited you to a private conversation'],
 			['test', 'Test user', 'Test user invited you to a private conversation'],
@@ -126,7 +126,7 @@ public function dataPrepareOne2One() {
 	 * @param string $displayName
 	 * @param string $parsedSubject
 	 */
-	public function testPrepareOne2One($uid, $displayName, $parsedSubject) {
+	public function testPrepareOne2One(string $uid, string $displayName, string $parsedSubject): void {
 		/** @var INotification|MockObject $n */
 		$n = $this->createMock(INotification::class);
 		$l = $this->createMock(IL10N::class);
@@ -158,20 +158,15 @@ public function testPrepareOne2One($uid, $displayName, $parsedSubject) {
 			->willReturn($l);
 
 		$recipient = $this->createMock(IUser::class);
-		$u = $this->createMock(IUser::class);
-		$u->expects($this->exactly(2))
+		$this->userManager->expects($this->once())
+			->method('get')
+			->with('recipient')
+			->willReturn($recipient);
+
+		$this->userManager->expects($this->once())
 			->method('getDisplayName')
+			->with($uid)
 			->willReturn($displayName);
-		$this->userManager->expects($this->exactly(2))
-			->method('get')
-			->withConsecutive(
-				['recipient'],
-				[$uid]
-			)
-			->willReturnOnConsecutiveCalls(
-				$recipient,
-				$u
-			);
 
 		$n->expects($this->once())
 			->method('setIcon')
@@ -264,16 +259,15 @@ public function testPreparingMultipleTimesOnlyGetsTheRoomOnce($uid, $displayName
 			->willReturn($l);
 
 		$recipient = $this->createMock(IUser::class);
-		$u = $this->createMock(IUser::class);
-		$u->expects($this->exactly($numNotifications * 2))
-			->method('getDisplayName')
-			->willReturn($displayName);
 		$this->userManager->expects($this->any())
 			->method('get')
-			->willReturnMap([
-				['recipient', $recipient],
-				[$uid, $u],
-			]);
+			->with('recipient')
+			->willReturn($recipient);
+
+		$this->userManager->expects($this->any())
+			->method('getDisplayName')
+			->with($uid)
+			->willReturn($displayName);
 
 		$n = $this->getNotificationMock($parsedSubject, $uid, $displayName);
 		$this->notifier->prepare($n, 'de');
@@ -315,7 +309,6 @@ public function getNotificationMock(string $parsedSubject, string $uid, string $
 			])
 			->willReturnSelf();
 
-
 		$n->expects($this->exactly(2))
 			->method('getUser')
 			->willReturn('recipient');
@@ -381,20 +374,15 @@ public function testPrepareGroup($type, $uid, $displayName, $name, $parsedSubjec
 			->willReturn($l);
 
 		$recipient = $this->createMock(IUser::class);
-		$u = $this->createMock(IUser::class);
-		$u->expects($this->exactly(2))
+		$this->userManager->expects($this->once())
+			->method('get')
+			->with('recipient')
+			->willReturn($recipient);
+
+		$this->userManager->expects($this->once())
 			->method('getDisplayName')
+			->with($uid)
 			->willReturn($displayName);
-		$this->userManager->expects($this->exactly(2))
-			->method('get')
-			->withConsecutive(
-				['recipient'],
-				[$uid]
-			)
-			->willReturnOnConsecutiveCalls(
-				$recipient,
-				$u
-			);
 
 		$n->expects($this->once())
 			->method('setIcon')
@@ -902,27 +890,24 @@ public function testPrepareChatMessage(string $subject, int $roomType, array $su
 			->willReturn($l);
 
 		$recipient = $this->createMock(IUser::class);
-		$userManagerGet['with'][] = ['recipient'];
-		$userManagerGet['willReturn'][] = $recipient;
+		$this->userManager->expects($this->once())
+			->method('get')
+			->with('recipient')
+			->willReturn($recipient);
 
-		$user = $this->createMock(IUser::class);
+		$userManagerGet = [
+			'with' => [],
+			'willReturn' => [],
+		];
 		if ($subjectParameters['userType'] === 'users' && !$deletedUser) {
-			$user->expects($this->once())
-				->method('getDisplayName')
-				->willReturn($displayName);
 			$userManagerGet['with'][] = [$subjectParameters['userId']];
-			$userManagerGet['willReturn'][] = $user;
+			$userManagerGet['willReturn'][] = $displayName;
 		} elseif ($subjectParameters['userType'] === 'users' && $deletedUser) {
-			$user->expects($this->never())
-				->method('getDisplayName');
 			$userManagerGet['with'][] = [$subjectParameters['userId']];
 			$userManagerGet['willReturn'][] = null;
-		} else {
-			$user->expects($this->never())
-				->method('getDisplayName');
 		}
 		$this->userManager->expects($this->exactly(count($userManagerGet['with'])))
-			->method('get')
+			->method('getDisplayName')
 			->withConsecutive(...$userManagerGet['with'])
 			->willReturnOnConsecutiveCalls(...$userManagerGet['willReturn']);