The one kind of AI detector that could work would be if the AIs store some checksum(s) of each text they write. Then you can ask it if it wrote a certain text.
With the naive version of this, you only have to change one word to get around the system.
A better version is to checksum smaller segments. Maybe a "chunk size" of 50 words is good. If you find several such chunks in a text, it's pretty clear you have a slightly altered AI text.
This won't work, as local AI (the one I can run on my budget-friendly laptop without any Internet access) exists today and even beats GPT3.5 in some benchmarks.
With the naive version of this, you only have to change one word to get around the system.
A better version is to checksum smaller segments. Maybe a "chunk size" of 50 words is good. If you find several such chunks in a text, it's pretty clear you have a slightly altered AI text.