Discussion Card has broken "View Discussion" button

[mns-james-cross]

Describe the bug

When subscribed to Discussions for a repo, a card is posted in our channel. Since the start of this week, the layout of this card has changed, but the link to the Discussion no longer works:

Looking at the JSON for the attachment for this card, I can see that the URL field is empty:

To Reproduce
Steps to reproduce the behaviour:

1. Subscribe to a discussion @Github subscribe integrations/microsoft-teams discussions
2. Create a discussion in the repo
3. Wait for the card to be added to your Teams channel
4. Attempt to click on the action button at the bottom of the card labelled "View Discussion"

Expected behaviour
Button opens web browser to take user to the discussion

Actual behaviour
Button does not work