German cars have had that Paint Protection Film since forever. I've had the film discolor on my wife's A8 (after 15 years and ~140K), but I'm not convinced that it was from waxing it (wax didn't discolor it one the '93 Audi, and UPP, BF, and whatever I used before that haven't discolored it on the S8).
This won't really help the original poster, but the best thing is to keep the edges of the PPF sealed tightly to the panel so the dirt doesn't get underneath. Even just having heavy layers of LSP along the edges can help immensely.
mnewxcv- That piece is so small and seemingly easy to position correctly that I'd be tempted to just strip it off and replace it with a new one.