This is almost invariably SMBC images, I’m not sure if there’s something about them I’m not aware of, or if it has something to do with their dimensions (typically very long). It used to just shrink them down dramatically for display in the thread, which was understandable, but now it just mangles them, even when I try to use height/width to shrink them to a more manageable size (they’ll look fine in the preview, but once I save, it goes back to mangling them).
Heh, and now it behaves properly. Before it would shrink to that height, but then stretch to the full width of the comment.
Oooh, there we go. Originally the image was in a link back to SMBC, but I wanted clicking on the reduced imaged to cause it to zoom, so I moved the link to just the text, and then the stretching happened again.