For those of you still having issues, have a look at the logs when installing the built .deb. In my case the debian package wasn't installing because for whatever reason the kernel headers were missing.
To fix this:Code:apt install pve-headers
Now everything is back to working as it was, thanks for the help guys
This fixed it for me as well.
I first installed the pve-headers (I had previously only done the pve-headers-6.5.11-4-pve), reinstalled the built gasket .deb, rebooted and it was back and working as before.
Thanks for your help