I've noticed that Pinterest is now so over-stuffed with falsely attributed AI-art that it is spilling over to Facebook communities, where people will celebrate water colors and oil paintings attributed to painters who never did them.

The first thing an AI-blocker extension should do is thus to cross reference all images with Pinterest, and just NOT show anything that is available there. Harsh, but the user might then choose to reveal a hidden image on a case-by-case basis. Deviant art is another community that is now chuck full of AI images. People don't repost from there very often, as artists there tend to claim ownership of the images themselves, but it might be nice to block out their entire catalogue as well.