[SOLVED] Ubuntu 21.04: if Share Screen in Zoom does not work

1.  Log out of the session.
2. On the log on screen click the gear at the bottom.
3. No you can choose between the new Wayland and another option.
4. Don't chose Wayland. Choose the old version.

It seems that Wayland is not ready for Zoom yet. I hope that you see this before trying to share Zoom screeens in Ubuntu 20.04 ;-)