As soon as the extension exists, the websites will remove the tags, no site is going to willingly let themselves be filtered out of Google results, etc for something entirely in their control

AI art in its current form is an incredibly new phenomenon, maybe about a year or two old tops. If openAI have admitted there's no reliable way to detect chatGPT output, AI art is equally inscrutable to automated filtering.

tl;dr the world has changed again, we adapt

I mean, it wouldn't hurt to have it, but I doubt that it'd be too efficacious.

I've uploaded AI-generated images I've generated to two communities on lemmy that are focused on AI-generated imagery. My original image has the tags, but lemmy has built-in image hosting, which most people there use. It strips tags off the image (I assume to try to avoid people inadvertently doxxing themselves from photographs when they upload images taken where the camera embeds GPS location data in EXIF tags, which has been something of an issue in the past). Imgur also strips tags from uploaded images. I wouldn't be surprised if most image-hosting services probably do the same.

It's also a problem from a standpoint of AI training, because one of the more-significant issues that comes up is that you don't want to train AIs on AI-generated images, and people training AIs have no good way to filter them out either.