For me it was the "it's not x"/"it's y" stuff and some other structures Claude is very fond of using all the time. Perhaps humans are starting to write like LLMs!
But who knows!
The answer is none. LLMs haven't accurately modeled human writing for years, current models have been smacked on the head with the coding RLHF bat so much, they all write distinctly inhuman text.
People are nitpicking every tiny thing in their search for proof of AI. It’s not useful and ends up dominating the conversation. AI panic is degrading the value of forums at least as much as actual AI at this point.