Ad review and website categorization are two separate systems at Meta and they do not talk to each other. Your ads can be approved and running while your domain has been categorized which is why performance can fall off with no rejection, no email and nothing obviously wrong.
There is a place to actually check tho: Events Manager, Settings, Manage Data Source Categories
If the list is empty you are fine. If your domain is listed that means you are categorized and it will name the category it put you in. That means Meta uses and shares less of your event data, and since delivery is a machine learning system, starving it is what tanks performance as a whole
Takes about a minute and most people have never opened that screen
Source: r/FacebookAds · by /u/Illustrious_ip1028