In this fully-lit oblique view, you can see that she has some irregular pigmentation as a complication of the peel.  Follow from the front of her chin, along her jaw line up toward the ear and see how the skin color changes.

She was at a much higher than average risk of a noticeable pigmentation change because she had so much pigment in her skin before surgery.  If the skin has a noticeable change after surgery, it's usually that the peeled skin is lighter than it was before the operation.  The lighter your skin, the less pigmentation you have before surgery, and the less likely you are to have a noticeable change.

She was still an excellent candidate for the peel, however, because we anticipated such a marvelous improvement that we thought we could live with a little pigment irregularity.