I think we're talking about two different things. You're not noticing the forest for the trees. I'm talking about big huge macro effects that become more apparent when you zoom out, not less.

There is a difference in the gradients of color. One hasn't the guy looking backlit and one doesn't.

At default zoom the image is 20% of the width of my monitor so it's hard to see artefacts. When zoomed in the posterization is noticeable but jpeg at 85% is about as bad as webp. I don't see any substantial difference in lighting.