Download this picture and see it as a thumbnail, like in whatsapp or your phone gallery and you'll find that it shows another picture in the thumbnail.
If you can't see the thumbnail: You can simply do some changes in color, or do some filters on it using PicsArt and you'll notice the difference. I've searched the whole internet, but haven't got the answer yet. Please explain how is this happening.
Note: I know about the trick with PNG files, but this is a JPEG file and the trick works with this too. I added video a to elaborate.