As noted in some of the past replies to this thread, to get Teams videoconferencing to work on a Mac, you need to first turn off "Prevent cross-site tracking" under Safari Preferences>Privacy tab, and then click the Join button in the meeting invitation in Apple Calendar. (Doesn't work right in other calendar apps, and it has to be in this order). Select join through the browser (middle button). Trying any of the others two options yield no response. It no longer triggers launching the MS Teams app, but that’s okay since I need Teams for nothing else.
I make sure no other tabs are open in Safari, and immediately turn "Prevent cross-site tracking” back on after the meeting is over. This procedure has worked for me for several different meetings during the last two weeks.
Until Apple and Microsoft engineers can be civil with each other, that’s the best solution I can work out from this thread.