By any chance did you have an initial picture without your face?

Over recent years Facebook has been clamping down with those same sort of messages (sometimes it will appear after a few days or weeks for people I know) and for better or worse the main fix was having a picture with a face on a brand new account.

Older accounts don't have this problem though.

It's a similar tactic to how in recent years twitter lets you sign up without a mobile number but after some time you will suspiciously get your account locked until you "verify" with a mobile number.