You inadvertently answered a different question I wondered about: I'm on a Lemmy instance and your post is on a kbin instance. Now I know what happens when a non-link, self-post (whatever that's called) with image gets posted to a kbin instance and I see its preview from a Lemmy client.
I think I remember the images not previewing properly in the past but I got a preview just fine in Jerboa ๐