2014 audi q5, headlight lenses crazing/frosting from the inside. this is not water moisture, this is a defect in the lens material. the crazing/frosting of the lens decreases light output and scatters the light to where it affects oncoming drivers.
Interior surface of headlight assembly covers (lenses) showed significant pitting and hazing, as if it had been sandblasted, resulting in replacement under warranty because the plastic had degraded enough to reduce vision from headlights. these are sealed assemblies and there was no exterior damage. my suspicion is that the uv generated by the led headlight projectors is so high that it is attacking the internal surface of the plastic. dealer remarked that they had seen "a number" of these. q7 owners with similar led headlamps have also had this problem. problem is only really visible to owner if the headlights are on, and the owner happens to be looking at the headlight assembly while not driving.