Yes, I would personally count that as AI-generated content. At least to such an extent that, as I wrote in another [answer](https://meta.stackexchange.com/a/385500/369802) a while back, the LLM should be attributed as having written the text. Whether or not any site wants to allow that, is up to them, that can't be decided for all of them here on MSE.

In the above quoted answer, I also posted text that didn't need changing into an LLM and the quotes show that the thing makes changes that aren't needed. If you run a quote through an LLM with a prompt to edit or rephrase it, and then run the result through the same LLM with another prompt to edit it, *it will be edited or rephrased*. No matter if it's needed or not, LLMs like ChatGPT aren't made for spelling/grammar checking or only rephrasing or rewording those phrases that need it. They just do as they're told, and change the text, sometimes for the worse. This means that whatever you get back, will be completely AI-generated and no longer yours, even though the text you get back contains a lot of words similar to the original ones you put in.

I would argue that this means that for wording/phrasing, if you're not proficient enough in a language to know something is wrong or right from the beginning, you can not at this point trust the LLM to make the right choice for you. Ask it to rewrite an already rhyming poem 'to make it rhyme', and you'll get some suggestions that don't rhyme at all. Putting [this](https://ncf.idallen.com/english.html) poem which rhymes very well into ChatGPT and telling it to 'rewrite this so it rhymes' gives results that rhyme 'vague' with 'haze', and 'labyrinth' with 'smith'. The LLM simply isn't smart enough to choose the right words or phrasing, or recognize that what it was fed was already very correct. 

I'd ask you (and everyone else who's considering doing this) why you think there's a need to use the LLM for spelling/grammar. Especially for spelling/grammar, it seems like a case of 'when you have a hammer, everything looks like a nail'. LLMs like ChatGPT aren't specifically designed as tools for spelling/grammar checking. They just take a prompt and use some kind of statistical relationships they learned during training to make some text. 

Instead of using the LLM for spelling/grammar, ***just use a tool that's specifically designed for spelling and/or grammar checking***. Most devices and browsers these days seem to have default ones built-in, that give nice squiggly red lines when you make an error. Otherwise, there are plugins like Grammarly. There are a few advantages of these, the most major one being that do not make changes for you, they just give you suggestions. So you can always decide what to keep and what not yourself, and it is faster than having to compare two bits of text to see what changes an LLM made and if these should be kept.

The other serious advantage is that you get to skip the whole discussion about what should/shouldn't be allowed and it makes moderating AI-generated content a lot easier without having endless discussions about how much of a prompt should also be in the final text before something is/isn't considered AI-generated and thus could be removed on sites that have policies banning such content.