There was a database change or two around then. If people ran out of room or had a big database and didn’t want to wait for it to finish the migration, then interrupted it, shit happened.
I know not everyone agrees, but the HA database is for runtime data. Long term data should be stored elsewhere. If your database is over 2gb rethink your options and delete it. You have a (usually) small CPU and big databases slow stuff up, so keep your long term and working data separate. My opinion, but it has served me well.
I delete my database about once a year and have no problems. I don’t care at all what energy the wash machine used 2 years ago. It was 2 years ago. I know, I know, pretty graphs, show trends, worship the data, but just purge it. You will have less stress and live longer.