edit: here's the effect I'm talking about with lossy compression and adaptive quantization: https://cloudinary.com/blog/what_to_focus_on_in_image_compre...
The result is smoothing of skin, and applied heavily on video (as Youtube does, just look for any old video that was HD years ago) would look this way
That would presumably be an easy smoking gun for some content creator to produce.
There are heavy alterations in that link, but having not seen the original, and in this format it's not clear to me how they compare.