There's good and bad tools out there? Most free internet services that pop up on the first page of Google are in fact rubbish. But that doesn't mean there's good ones. I once tried tools for detecting AI text for a different reason and there were one or two who didn't have any false positives with the 20-30 example texts I tried. Schools and universities have come to use the same tools. Seems they also look at how people are typing, that's pretty much 100% accurate, but people do both.

There's also crazy different approaches out there. Like looking at the probability distribution of the vocabulary and see if that matches ChatGPT. And it'll be a certain unique probability distribution since that's what ChatGPT is. It has to leave a fingerprint, since it's picking the words based on probability. And there's more good strategies. We have one or two open-source tools which demonstrate how it can be done without AI. There's of course also the option to train another AI model / classifier to figure out what constitutes AI text and what isn't. That also works.