I tend to think this is related to the following issue:

• Yellowish border appears on map focus (mobile) #4895

I believe this is related to a11y (accessibility) definitions of Firefox and mobile chrome.

Ok, I think I've found the issue:
The maplibre css defines a hover effect on the ctrl buttons, which is discouraged on mobile, because mobile browsers set the hover state on click, but only reset it when clicking on some other element, not when dragging the map for example.

CSS that causes this effect

.maplibregl-ctrl button:not(:disabled):hover{
            background-color:rgb(0 0 0/5%)

This jsbin shows the fixed behavior.
I can propose a patch for this issue later.

Can you link to an article about the discouraging you referenced above?
Also, I think I still see the issue in the jsbin you linked...

I've corrected the jsbin link. I found for example this article related to the issue.

Recording of touch device behavior with the patch:

Which jsbin has a fix that works on mobile?
My chrome on Android is still showing the hover effect after click...

The jsbin https://jsbin.com/dedemareco/1/edit?html,output shows the behavior from the fixed video for me.

I've also created: https://jsbin.com/wedujofugo/1/edit?html,css,output which has the full updated CSS from #5285

Using both links I still get this after clicking the + button, on Android (chrome), is this expected?

I cannot explain this.... This is a video I just recorded of https://jsbin.com/wedujofugo/1/edit?html,css,output with Chrome 131 on Android 15:

It works nicely there now.

I have Android 14 but chrome 131 as well... Weird...

I've also tried on Safari/Ipad now, which shows the fixed behavior. Maybe you can try with Firefox/Chrome DevTools on Desktop, they can emulate touch device behavior too. For me, they also show it fixed.

It's probably an improvement, so I'll merge it as is, you are welcome to continue try and reproduce what I'm seeing on your end to be able to solve this for more devices...

Thanks for your support!