I've seen a number of posts (elsewhere) about Facebook abruptly closing their accounts (with no recourse for recovery). My own account has been demonetized because of posts I've made long ago. (Not that I was making much to begin with.)
I think FB is using its AI to "clean up" longstanding accounts (copyright violations, verboten topics, etc), and it's closing accounts as a result.
If you care about your past data, I recommend downloading your account data soon.