Using linux, when you share your desktop in a video call it is black with a mouse you can move.
I spent a lot of time trying to find a soution, and all the posts were closed without a solution.
The solution: Enable Pipewire https://www.freecodecamp.org/news/how-to-fix-black-screen-on-google-chrome-on-linux-os/
chrome://flags/#enable-webrtc-pipewire-capturer