What process did you use to upgrade? Time machine restore? If so then you should remove everything roon related and reinstall from the download on roon web site then recover from a ROON backup. You do have a backup I hope. Time machine is not a good option and is warned against by roon.
You could just try renaming the Roon ~/Library folders and reinstall too.
Just for info…I purchased MacMini M1 16/256GB RAM/SSD and left it at BigSur as shipped but updated to 11.6.1
I installed a fresh Roon version from the website, authorised login and proceeded to scan and import all ~340K over from my Win10 share with no issues (still adding about 100K tracks to go) but I don’t expect any issues.
One thing with the M1 is you share the available memory with the display and the rest of the OS takes a good chunk of it too.
8GB really isn’t enough even just running up the core and the client with only steaming data and no local library its was already using a fair bit.