Not sure if this is the right place to report this. If not please give some directions. Anyway:
Current behaviour:
When clicking on the "Share content" icon a message ("We need permission to share your screen. Go to Security & Privacy > Screen Recording to give permission and start sharing.") appears and none of my screens/windows are available to start sharing. Teams already has the permission for "Screen Recording" in the "Security & Privacy" preferences dialog. However, as soon as I open "System Preferences.app" (any submenu) and try again while it is still open everything works as expected. I can consistently reproduce this behaviour.
Expected behaviour:
Screen sharing works independently of the "System Prefenrences.app" once the "Screen Recording" permission has been granted and Teams was restarted.
macOS version: Catalina 10.15.7 (19H15)
Teams version: You have Microsoft Teams Version 1.3.00.28778. It was last updated on 08/11/2020.