After over 70,000 miles the sunroof in our 2011 Outback starting humming like a bunch of bees at speeds of 50 mph or more. I searched on the web for others experiencing similar problems and read an article by an owner that said his sunroof quit humming after he had it washed. So I washed the front of edge of the window and the seal and, to my pleasant surprise, the noise is gone.
Great, hope this info helps someone else.
I had the same problem and it required me to lubricate the slides. 2 years later, I had to repeat. But that was a Jetta.
While you’re at it, have you flushed the sunroof drains recently? More on how to do this if anyone is interested (start a new thread).