Desktop icons in Zorin OS suddenly disappeared mid-session and do not reappear after reboot, despite being enabled in Zorin Appearance. At the same time, gjs showed unusually high memory usage, which made the system unresponsive and required a forced restart using Alt+Print Screen + REISUB, but I am not sure if it is related.
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Did You received any Updates before that? Did You tried it with disabling the Zorin Desktop Icons Extension and then enable it again? You could try it with a Reinstall:
sudo apt reinstall gnome-shell-extension-zorin-desktop-icons
If that shouldn't help, You could use as an Alternative one of these Gnome Extensions as a Replacement: