A Microsoft communications service that provides communications capabilities across presence, instant messaging, audio/video calling, and an online meeting experience that includes audio, video, and web conferencing.
I have the same issue with Ubuntu 18 and ThinkPad. The same for my colleagues in my organization.
The following link shows that at least 45 persons have the same issue on different HW and Linux distributions, with the majority on Lenovo/Ubuntu
In my case system is affected even without screen sharing, just a normal voice call and no key pressed during the call. However, after the call system is completely blocked, repeating every keystroke multiple times. That happens in about 60-70% of all my voice calls.