I made a rough model of a 4-legged animal. I did it using a mirror modifier to mirror the left and right sides of the animal. In object mode, I right clicked on my animal and chose "Shade Smooth". Results:
Why is there a discoloration in the center of the animal?
So there is discoloration in solid mode because there is a ridge and depression in that area... But what is the cause of the ridge and depression? According to my wireframe, there is no depression in that area. The render is wrong. The head is supposed to be smooth.