Hi,
Probably not "the free disk space issue" as apparently that is fixed.
https://mrmacintosh.com/big-sur-upgrade-not-enough-hd-space-serious-issue-possible-data-loss/
So then we're back to the "it happened before" thing with Big Sur guests (I certainly have had to rebuilt BS guests due to similar experiences)
Hope you have a backup.
--
Wil
