iMac 21.5 inch, late 2013 with Quad core Intel core i5.  Catalina 10.15.7.  I am on Satellite ISP, former Wild Blue/ Exede, now Viasat.  Things deteriorated to where I could only open in Safe Start, which I used to clear all traces of Teams (hard because it inserts in half a dozen places).  I eventually got back to some function.  Teams disabled both my audio and video, stating that I needed a Teams compatible version of each.  Maddeningly, Teams has become monopoly vendor to both Federal and State government, and I find myself frozen out of meetings I formerly joined with no effort.  I can get onto some with telephone connection, but virtually impossible to participate.   Teams is Version 1:00.333671.
With my satellite, I have never been able to use Skype, which is a bandwidth hog.  I have too slow an uplink to have more than placemaker.  I suspect Teams is doing the same to me.  Teams is a large application file: 254 MB.