I have this on my aftermarket lights. More on one side than the other so I leave one of the rear covers off which helps. Apart from that turning the headlights on wherever you go will help, or use a hairdryer to dry them out
My headlights are genuine GTI.
The problem turning headlights on while raining makes it worse. Tried hair dryer job, and it helped. All mist gone, as soon went for drive with lights on, mist came back.
After about 1 hr, parked on drive, mist disappeared from both headlights.
I put them headlights about week ago, went few times trough car wash, no problem, rained couple times no problem. But yesterday when sky opened with heavy rain, headlights started misting up.