In my opinion AI assistance tools should be allowed as long as they're used in moderation. Here's a few instances of AI I've commonly seen which personally I'm not a fan of, such as:
Artwork - it gives an incredibly low effort vibe, a paid product should look professional and its thumbnail should be representative of what's being sold.
Descriptions - AI does not understand your product as well as you do, it can only make assumptions and provide vague explanations of what it does. Using it to clean up a handwritten description is fine as long as it's verified first, but yet again, the "AI sentence structure" gives a low effort feel and should be adjusted. Another fair usage of it here would be asking for a product description structure, so you're writing your own content but using AI for inspiration.
Code - any developer who's used AI code generation before will be able to identify it fairly easily. Customers who've knowingly bought code which is mostly AI generated should rightly feel deceived, as you're buying the creator's code. That being said, I think it's fair to use AI assistance tools like GitHub Copilot - you were going to write it anyway, might aswell improve productivity.