Solar Pathlight Solar panel fading..?

Hello, I started noticing one of my solar path lights Solar panel discoloured. Almost looks like the black is fading around the edges. Anyone know why that is occurring. They are still under warranty and all lights were purchased at the same time (6 lights). Just have the issue with one light. See attached pictures. I will be calling support as well to see what they say, but curious what others thoughts may be. Thanks :slight_smile: