A family of Microsoft relational database management systems designed for ease of use.
It's a Windows 10 update that caused this issue. If you check out https://www.devhut.net/2018/06/13/access-bug-database-is-in-an-unrecognized-format/ it seems it is caused by KB4100403.
The issue has nothing to do with Access, Office, but they are sadly impacted by it. The version, edition, bitness of Access makes no difference. The only thing is that if you have a single Windows 10 PC using your db, then this becomes an issue.