After investigating more I’m having a moment of thinking is not worth adding another thread to the already too long lists of not totally useful threads on Database corruption shenanigans to the forum 
But in the hope it will help in the future there we go…
Now I think is not an OS16 update related issue but rather data corruption due to my tests for a new Gas meter via door magnet sensor. As it is the only other change to my HA installation in the past 5 days that may have affected the energy dashboard data in the DB.
I have also discarded disk issues, since I’m running HASSOS on a VM on proper hardware and I have not had any power loss or unclean shutdowns in many months. Database size is small c. 370MB
After doing various resetting/deleting/restoring tasks and running a pragma integrity_check; on the DB, is confirmed that the “Database disk image is malformed” aka corrupted, so I’m back to square one.
Is clear now that I need to focus on trying to fix it, this thread seems to be a good source.