Home assistant rolled back to a previous version without permission

The day after I migrated from VM to Blue, Home assistant Core and OS have spontaneously reverted back to older versions. When I say migrated I mean I shut down the VM and then restored from snapshot on the blue. (latest version). Everything worked fine after I went around to my wall tablets to modify the mqtt settings to the new IP address etc.
The next day I was presented with an outdated version of HA and the absence of HACS even though the HACS integration and custom components file where still present. After updating the Core and OS and removing all traces of HACS and reinstalling it; everything seems to be fine. Just wondering if anyone else has experienced anything like this?

Similar behavior for me too.
After a reboot I always have OS 11.5 even though I updated to 12.0 before.
The system also runs on 12.0 for a some days, only as soon as I reboot my Oracle VM (VirtualBox VM 7.0.14) I have 11.5 again and have to update to 12.0 again.
After the update it also shows 12.0 normally, also in the terminal window.
This has happened three times already.

How to permanently update to 12.0?