This muddle of an article makes it totally unclear to me if this GUID is attached by the AI generation call or every image I edit in MS Paint. I'm going to assume the former unless they release a clarification.
Edit: Actually trivial to test, just save an image of all black and see if it suddenly has other values on save.
Assuming the watermark works like the upcoming AI watermark for text, then it uses the content's entropy to embed the information. An all-black image doesn't have much entropy, so it's unlikely you'd find anything.
I guess that makes sense. So import an image of the mandelbrot set you generated and save it, and see if any pixels change.
> Edit: Actually trivial to test, just save an image of all black and see if it suddenly has other values on save.
Did it?