Well I just checked. At least, since they also posted the covers, the name of the author's going to be pretty visible alongside their art. And they didn't shit on the pictures by compressing and converting them badly. That's quite common.
I don't really get how these people profit from this, but much of this art is shared by Erenisch on their socials media, and these galleries don't contain the text, so it's more publicity for the complete "products".