This issue was prevalent a few years ago when RV manufacturers started using front caps with deep color infused fiberglass, sure looked nice at first but the vast majority started exhibiting the same issues you have noticed on your Winnebago. The only real answer was to start painting the front caps which most of the major RV manufacturers started doing about 5 years ago.
I thought for certain Winnebago was already onboard, sadly my friend is experiencing the very same issue on his 2018 Winnebago, entire rig is blue and was built in 2017. I have noticed many of the other colored Winnebagos doing the same thing as well, he is working with the factory and hoping for a positive resolution although they seem to be dragging their feet thus far.