I believe that this kind of unfriendly UX helps companies like Facebook only in the short term. Long term these minor annoyances add up and people eventually go to a different platform.
I believe that thing does stuff like making sure Facebook can access the link and checking OpenGraph tags and so on, so you can see how Facebook will "preview" links to your site if people post them.
"We can't review this website because the content doesn't meet our Community Standards. If you think this is a mistake, please let us know"
So an unhelpful; start but a start to understanding what may have happened.
Link: https://developers.facebook.com/tools/debug/?q=https%3A%2F%2...
My guess is that FB should have blocked a sub-domain but instead blocked a whole domain because of a small set os users.