GIMP I've used for years and years, never heard of photopea, was the comment a SPAM Ad spot?

No, photopea is pretty well known now. Mentionned a few times on HN too

Photopea is almost more well known than gimp these days.

Who knows why you're being downvoted, and I'd say it's _more_ well known than GIMP.

My sister has used Photopea. She's as far from a sophisticated computer user as you can get. Regular people can stumble across Photopea, they certainly don't know about GIMP.

Haven't used photoshop in 10 years. I have gimp, never use it. Paint.net is my basic image tool, along with IrfanView, for which I have a license circa 2004. I also use Scribus, FOSS version of InDesign. But never heard of Photopea until today...

It's not free software though

personally I prefer https://pixlr.com/, but then it's mostly because I learned to use it first.