When clicking “edit” on DALL-E 2 generations, the image in the editor gets JPG compressed. This doesn’t affect images uploaded by users, only when clicking “edit” on DALL-E 2 generations. This could be a result of the new editor, or it may have always been this way.
I also just discovered that wherever you edit gets JPG compressed. The rest of the image outside of the 1024x1024 generation frame stays untouched but inside you can see the blatant artifacting.