The issue with Ubuntu 22.04 is that it now uses a display feature called wayland by default, while in versions prior to 21.04 Ubuntu defaulted to using xorg as its display server. Wayland does not support screen sharing by default (until now, at least!).

To check which display system your Ubuntu is using, please enter this command

echo $XDG_SESSION_TYPE

If the above command outputs wayland, your system is using wayland.

In order to use screen sharing, we have to disable wayland and enable xorg (x11). To do this,

Please go to this file

sudo nano /etc/gdm3/custom.conf

Uncomment this line.

WaylandEnable=false

Reboot your system.

Voila! You can share your screen. You can confirm this by re-entering this command.

echo $XDG_SESSION_TYPE

Now it should display x11.