Teams always has been shit with Firefox, while there is no reason to be shit. Like people said higher in the comments, if you change the user agent to edge magically new features are enabled.

Also Microsoft claimed to support Linux while in reality they made some half assed desktop client, and dropped support about a year later.

Slack was so much better, I really really hate that our office went with teams. Also for some strange reason teams is the only “website” that seems to crash my entire laptop once in a while and its the only app that makes my phone super hot.