Look at this fucking guy. Likely not a bot. But is an example of someone who is posting pattern is suspicious
You have just defined why your method doesn't work.
There is no issue with random people using LLM to craft their messages. The issue is using a network of bots to promote the latest marvel movie
You either detect AI by their language or you don't.
But, I think, I know what you mean. Your idea is like Bat-sonar, the super-totally-not-magical computer he built in the second or third Nolan film that allowed him to spy on everybody and thus detect crimes faster.
You want a system that would monitor ALL content online and detect "patterns". Like, "huh, weirdly, we have XXX number of people writing positively about the new JJ Abrams film", or "check it out, in the past hour we've had 43243 comments negative about MAGA".
Right?
If so: mate... You require literal magic to pull it off. WAY too many false positives or just impossible to trace dependencies. You would have to not only monitor for these patterns, but also associate them with any real-world events (ALL events), because maybe a Polish nationalist politician said something about the financing methods of their military, which got popular on russian Twitter, got a funny anti-MAGA retweet by a Ukrainian, ended up as a reaction video on British TikTok, and got posted to Reddit where it got upvoted to r/All and received 43243 100% legitimate comments complaining about MAGA.
Funnily enough, if anything, MAYBE a complex enough AI system would be capable of finding these patterns, but there's absolutely no physical possibility of humans doing that.