Indeed, the problem is back, and IM(H)O it has nothing to do with the version of TEAMS you run on your Linux box, or the configuration of the browser. Some genius at Microsoft decided to process a link in the form
https://teams.microsoft.com/l/meetup-join/....
differently when the browser runs under Linux.
If I click on a teams invite on any of my Windows machines, I land on a page w/ the usual choices: use the app or use the web version.
The same link under Linux (from Chrome or Firefox) show a choice for 1/10 of a second, but w/ no time to select it almost directly goes to the web version (or croaks w/ a typical inane message).
This is NOT what should happen if the Microsoft software architects had a working brain and would use it.
This worked fine until a (few?) month(s) or so ago, since I tinkered w/ xdg-open to catch a msteams://xxx specification.
Why fix something if it ain't broken and in the process bear things - the web version is clunky at best, and no I do not want to run everything under a browser.
I can go to the calendar of Teams itself I can join a meeting via the ID and passwd, but why is teams.microsoft.com making the wrong decision for the user instead of giving the choice avail under Windows?