Absolutely nothing wrong with the language of that English sentence, only your comprehension.
A large language model AI has no issue with it.
User Is this sentence in english correct, "What is this policing who qualifies to post here all about?"
ChatGPT Yes, your original sentence is grammatically correct. It may be considered informal, but it effectively conveys the intended meaning. If you prefer a slightly more formal or polished version, you could consider this revision:
"What does the policing of who qualifies to post here entail?"