I solved this issue by purchasing an $800 eGPU (Blackmagic) and telling MacOS to prefer the eGPU for teams.
Before the eGPU my 2019 MacBook Pro 16" (32GB/i9) fans would run at 4500-5k RPM within 60 seconds of a teams video call starting. This is a very audible level for the fans to run at. After switching to the eGPU they run around 2-2.5k for the calls regardless of how long they last. At this speed they are not audible at all to my ears.
That's right, I spent $800 to solve the fan noise problem caused by Teams.
Also, none of my other applications with video had/have the same problem (Zoom, Google Meet, etc.)