Just a hunch, but did you have Facebook installed on an Android device? There's a nasty malware going around infecting older versions of Android (that don't receive security updates). It takes over your Facebook account, posts malicious links and spam to all your friends. Phone is sluggish as hell, but works.
Check if any of your friends have received malicious messages and links from your Facebook account.
The malware even manages to disable Google Play Protect. It's detected by Malwarebytes, but it returns after a restart.
EDIT: I hope you get your account back. Maybe if you're able to pinpoint that some malware took over your account, facebook support would be more sympathetic? I sure hope they have some process in place for accounts that fall prey to these malicious apps.
Check if any of your friends have received malicious messages and links from your Facebook account.
The malware even manages to disable Google Play Protect. It's detected by Malwarebytes, but it returns after a restart.