Just look for the em dash. AI loves them. No amount of pleading with it not to use them will help. Nobody knows how to search / replace them. Well, not your regular non-cretinous mentally stable individual anyway,
Maybe I'm wrong here, but I recall recently asking Claude to write something for me and telling it not to use em dashes, and the resulting text did indeed come back without any em dashes in it. So, perhaps it's not quite as good of an indicator as it once was.