Using an LLM to prove text is human by asking another LLM to sound human feels like two mirrors facing each other. You mostly learn how good the illusion has gotten.

This is a losing game for Pangram

There's no special "humanity" quality in text. If a human can write it, there's no reason a sufficiently strong pattern matcher can't write it too.

This will be an ongoing battle for a long time. Happy you were able to get them to make the change.