I've noticed sometimes that when Cloudflare optimises images and serves up their own WebP versions of your existing images, if you go to save it you get the original jpg/png back.

Presumably the HTTP request that gets sent when you save an image sends different Accept headers.

Doesn't seem to work all the time, but presumably thats down to a combination of different Cloudflare settings, origin server configuration and what format the original image were in too.