This is a reproducible error. I suggest creating a separate Activity to try this so you can delete the corrupt Activity and restore your Desktop if necessary.

Add the Digital Clock Widget to the Desktop. Move it to a corner, any corner will do. Then, resize to try and make it full-screen. At about 50% you will lose your desktop.

To recover:

Code: Select all

sudo systemctl restart sddm

and re-log in.

If the Desktop does not come back then you could delete the corrupt Activity.
Reference: https://www.kubuntuforums.net/showthread.php/73458-Help-Lost-my-desktop

-=Ken=-