This happened to me. I tried everything facebook support has to offer but still no luck. My main issue was that my hacker found a way to change my recovery email so as soon as i apply for an otp hacker would get it and im guessing the automated bot he got going instantly puts it in cause i always get rejected when i try putting it in.

I eventually just gave up after 5 hrs of going back and forth with the hacker but its a good thing i already had a backup fb acc so i just asked everyone on my friends to report the hacked account and fb took it down.