I just tried it with the official app. It does have a banner by default if you download an image. The banner says what sub it’s from on the left, and it says “Reddit” and has the logo on the right. You can turn the banner off in the settings. But the banner also doesn’t cover up any part of the image itself, so you could also crop it out.

I actually don’t hate this implementation. Having a Reddit logo cover the content would be dumb, but this post could also be rage bait, since I haven’t seen this happen personally.

Edit: I want to clarify that the first time I downloaded an image it told me there was going to be a banner, and that I could turn it off in the settings.