Not every generative AI model will watermark. Especially not adversarial and disinformation models.

So as usual, exactly the things you want it to work on it won’t.

It actually might make the new horrible world even worse. Imagine the populace getting used to a AI image detector flagging things as fake using this fairly easily defeated GUID marker system. Most people are just making memes or cat videos and don't even try to remove this so eventually the populace starts to believe these things actually work.

Now some one slightly more sophisticated starts creating deepfakes of a woman and uploading them or fabricating video of an political event without this marker. The subject protests it's fake and AI generated but a loud majority of ignorants feed it into Microsoft AI detector and call you a liar and say it's confirmed real. Most people don't know any better and eat it up because a computer said so.