I think it's because I accidentally uploaded a really low-res version which is probably no better than cropping the initial xitter screenshot above. That and it is an ad and therefore generously retouched.

That's understandable, her feet and hands both look very strange, that's usually the biggest giveaway for AI. Her right hand is angled to show not enough fingers, and her left hand is bent the opposite way of what you'd expect and looks like a foot. Her foot looks like she has a tiny big toe, overly curled other toes and no heel. The reflection of the cheese on the under side of her forward pointing leg makes it look like she has an extra knee on the back of her calf.