Modern yachts are fitted with a combo deck and steaming light, they look great yet the black plastic they are made from quickly becomes a black crayon in the UV.
You probably don't notice it from the deck, yet I see the damage done to the sail up close. Those black marks don't come off either, as in the first picture, the second pic the marks came off, but look at the damage on the sail.
What to do? put a wear patch on the sail like you do for the spreaders, or put a nice smooth stainless bracket over the light.