Earlier quoted context omitted.
I caught it on my Android 12 without full screening. He's talking about the background, not the foreground. The backgrounds color noticeably changes from shot to shot around edges.
I have to zoom in to really notice that. But both the jpg and webp have distortion - webp slightly more. Both have difficulty with edges.
There is a difference in the gradients of color. One hasn't the guy looking backlit and one doesn't.