You can try to disable some of the preinstalled and enabled Zorin extensions for testing .
With extension manager you can disable them at tab "installed".
You can install the extension manager with
sudo apt install gnome-shell-extension-manager
Since I test it with disabled gnome extensions except for Zorin taskbar and Zorin menu I had for 4 days no more session crashes in my live session with Zorin 18 boot stick. Before the gnome session crashed nearly every day, especially after suspend, in the last month.
It's a shame not to have all the helpful features, of course, but personally I find the completely unpredictable crashes worse (damaging my usb boot stick and computer because I have to make a hard shutdown then).
You could then gradually re-enable individual extensions to see if the system still works.
Hopefully there will be a solution for this crashes soon!