Interesting hypothesis! I find that my internal sense of whether the article is AI almost always agrees with Pangram when I check it, and almost never triggers on pre-2024 text, even if I didn't know beforehand when it was written. I think this cuts against your hypothesis -- if I was just recognizing a generic style of writing, I would expect it to fire on pre-2024 text, and if I was just recognizing text written in 2026, I would expect it to fire much more often when reading blog posts of already-established writers who I trust.