Joking aside, I have found myself recently using phrases and styles of turning a phrase and stopped myself asking, "since when do you say that?"
Since I've spent countless hours talking to LLMs, that's when. I even had a multi-hour conversation with ChatGPT about my idea for "perfectly flawed" lab-grown diamonds, several months ago and was excited to finally find a place to talk about what I learned, hence the comment you attribute to being from an LLM.
I'm probably not an LLM, nor did I generate a response for this thread using an LLM, but you've just made me really self-conscious about how now humans, or at least myself, have to be wary that we don't start talking like the LLMs that are supposed to be talking like us.