I tested the day 1 when Nano Banana Pro was released and it worked. It still works today for Nano Banana 2.
I didn't post this anywhere because I (arrogantly) thought saying it publicly would make the internet worse. But it was pure arrogancy: if I came up with this the first day then of course other millions of programmers did too.
That being said, it'll introduce the typical artifacts from SD models and that might be detected by other methods (or just by zooming in a lot and looking carefully).
Never released it, but it was obvious to most people in the SD community that denoising using a diffusion model was a relatively trivial means to beat most steganographic watermarks.
Don't sell yourself short. I'm sure it was only hundreds of thousands.
In my tests the image looks clearly distinct. In other words, if you can tell the difference then it isn’t a good test.