I installed the Monterey Public Beta today and the tab groups are working for me in that environment, but still not in Big Sur.
DanAW
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution
Post
Replies
Boosts
Views
Activity
What I find interesting about this is that I have 2 MBPs (2016 and 2020 both Intel) and the 2020 is working as expected but the 2016 is not. I don't know what that means in the big picture, but it is not widespread on all Intel Macs. Good stuff...