There is a haze on the top half of Starman's windshield? It was not there in the first day o fthe launch and the video feed. It looks like fogged window, but assume it cannot be that. What is it and how did it form?
My (somewhat educated) speculation: deposited contaminants due to outgassing from the various polymers on the dashboard and/or the hood. Vacuum and UV exposure tend to break down nearly every polymeric material. The volatile compounds that fly off in the process would deposit themselves as a haze on the windshield.
As a side note, this is one reason you see very strict material and process control for any space vehicle that has sensitive optics. You don't want to fog up a mirror on a telescope because you put some piece of silicone near it. See this linked question provided by uhoh for more info on the outgassing problem.
I've personally witnessed a similar phenomenon. Car Windshields are not solid glass, they are two layers of glass sandwiching a layer of urethane in a molecular bond. I was once in an armored vehicle that hit a landmine and the pressure and heat differential between the outside and inside of the windshield caused the three layers to de-laminate. It seems like an odd thing to notice during such an event but I remember the windshield (about a 4 inch thick windshield mind you) in front of me instantly "fogging" up about as fast as you can snap your fingers. It wasn't really fogged, it was the three distinct layers between the heavy plate glass and urethane separating and off gassing due to heat just enough to lose some translucency and look foggy.
Its possible that between out-gassing caused by vacuum's effects on the urethane and thermal differential between the two pieces of glass that its 3 layers would de-laminate without shattering in much the same manner.