Here’s a quick one that should help some folks.
We recently enabled Office365 teams for a group of testers in our environment. A couple of our users, who use Linux as their primary desktop OS, noted that running with 3rd party cookies blocked in their web browser prevents Teams from loading successfully.
Working with Microsoft, we identified a group of exceptions that can be added to Firefox to allow Teams to load up with a 3rd-party cookie block in place. Here they are!
https://.asm.skype.com https://login.microsoftonline.com https://.teams.microsoft.com https://.infra.lync.com https://.teams.skype.com https://.sfbassets.com https://.skypeforbusiness.com
Make sure to enter them exactly as listed.
Linux desktop users are restricted to the web interface only since there is no desktop client for Linux like there is for other platforms. If you agree that there should be one, please go vote for this uservoice item to encourage Microsoft to put one out.