My test setup:
Windows 10 Laptop with teams app and external monitor.
iPad Air ios 12.4.2 with teams app
laptop and iPad join team video conference
ipad shares photo
Video streaming on iPad stops
No dual screen on laptop with external monitor
with reverse situation (laptop shares photo), the same situation: video streaming stops.
During the video conference I can only add ‘known’ contacts (only AD contacts).
Video/Audio latency is more observable that with competing video conference systems.
Video quality is less than competing video conference systems.