Language is a living thing. At one time saying 'cool' to mean something was neat wasn't a thing. Then someone used it that way and it spread throughout humanity (or least English speakers in the US).
This means as people use AI and read AI we'll start speaking like AI just as much as AI speaks like us. ESL people tend to have it even worse as they commonly speak a more proper subset of English and get identified as AI quite often.
The Panagram CEO was saying some rather dumb shit recently that they have high detection rates of AI because they can put in documents from X years ago and they are not detected as AI. This tells you absolutely nothing about if a recently written document is human or AI written at all!
Total snake oil.