If you check the /FacebookAds reddit forum, you'll see that about 50% of all accounts were recently disabled. Most of this is to verify that you are a human (not a fake acct) and that you are who you say you are. Most people need to upload ID and a screenshot of their account to prove they are not hackers from Gezhenzhia. FB had recently been attacked by fake Russ accts, they claim. Why a hacker would want to advertise your books ... is beyond me! but, it seems they think so.
About 20% are from real problems (alcohol, guns, anything that kicks out). Keep in mind, the world's 3rd most profitable company doesn't bother to employ humans. It's almost all run by algorithms. Computers are deciding if you've made a bad advert. It takes about 3 weeks, but most accounts get restarted. Of course, then your ads are broken and you need to start over.
Such is life.
Even though my account is not disabled, I've started looking for alternatives to FB. They're unstable and could disable any acct at any time. Some have reports 8+ disruptions in the past year.
Alternative ads are hard to find. Running ads in genre magazine did well for me (expensive, though). Still exploring Bing/MS ad network, Google and other avenues.