Funny thing that lemmy does: if you create a post with an image but no link, a link to the image will be added when federating. But not on the origin. And the url is different for some reason.See:
@npub1u6sv...fj0e which appears as a link to a jpeg bbf-b25 on lemmygrad.ml.
But: Open that post,
@npub1cn4k...qxq0, and the jpeg is f80-2ba, and the link is gone. It's a normal self post.
This has bugged me for some time, I don't like seeing the images appear as links, and wandered how they dealt with it. Short answer: nope. It displays wrong on every federated instance because it's the AP object that's bugged.
The two jpegs are byte wise identical, just different URLs.