It's not just that they are (somewhat) unusual phrases, it's that ChatGPT comes up with those phrases so very often.
It's quite like how earlier versions always had a "However" in between explanations.
We asked ChatGPT to explain the meaning of "come what may" - a phrase it generates very often in lyrics - and it responded by needing proof that we were human.
It's definitely a watermark.
It's not just that they are (somewhat) unusual phrases, it's that ChatGPT comes up with those phrases so very often.
It's quite like how earlier versions always had a "However" in between explanations.