For the longest time, via the internet, I kept watch on PC availability & pricing, in-part to encourage my brother to upgrade his Starflyte to a PC. I had seen maybe 6 PCs where the Diamond shield had turned a dark brown, like it was burnt from sun damage. I wonder if that level of damage can be removed safely. I imagine it would not peel-off, rather requiring aggressive scraping.
I had a little taste of removing via scraping, a 3M product from the rear deck lid of a Saturn Sky, a product similar to Diamond Shield that was badly sun damaged. That was a very serious project for me. Two small areas took me days to remove.