This is the issue. It's not that this is "LLM writing style". It is just formal writing. The thing is most people write like third graders, so these stick out with good reason, just not that 'it is AI'.
In general there aren't good ways to tell TBH. Literally giving it the command to 'not write like an AI' would make half of these disappear.
Having the AI edit a text for you would add some of these. Not because it is AI, but because that's proper writing.
Yeah, I agree with this. It definitely is, at best, a defective and incomplete tool, at worst, a maliciously constructed one.