Ask the photographer!

The reason is the perspective effect, that is, the near is big and the far is small, which is especially obvious in the lens with short focal length.

Taking pictures of people is different from taking pictures of cuboids. Perspective effect works on the premise of people's understanding. There is no definition of "up" or "down" in the cuboid itself. It is an effect to toss and turn photos.

Similarly, if the person's photo is rotated by 180 degrees, people's understanding will change with "up" and "down", and the obvious height will not become the obvious short effect.

You have no idea what's going on. You'd better practice before asking questions. You'd better talk about your country.

Of course, shooting with head up and head down is not the difference of camera rotation 180 degrees, but the change of position, and more importantly, the change of position relative to the light source.