The issue isn't that it's a gradient, the issue is that it has noise.
That noise is the thing the AI picks up on in training and magnifies to produce the patterns on faces seen here >>107058901
color picker with a tolerance of 0 can show it but you can just see it with your eyes if your display is calibrated right and you're not color blind.
Try scrolling up and down with the picture enlarged, that can make it more visible too. I took the color out of it which might help if you're colorblind