I'm sure somebody has posed this exact question, but searching in the Affinity forums is a real trial. There doesn't seem to be a way to search for the phrase "undo crop."
So, having cropped an image in Affinity Photo and saved without saving history, how can I get back to the original image the next time I open the file? Yes, "Unclip canvas," but that puts some annoying transparent "stuff" around the original image.