How old is the vehicle in question?
New vehicles have a load of chemicals that need way more time to cure out than the manufacturing process allows for. Adhesives, solvents, plastic mold release chemicals, etc. They are the toxins we call "new car smell".
Newer vehicles release more, and they these chemicals accumulate on all interior surfaces, but are most noticeable on glass as a film.
On older vehicles it is greatly reduced unless you have a heater core leak it some other accumulation of fluids in the cabin. The sun will heat them up and they'll evaporate into the car's interior air space and cling to all the surfaces therein.
If you truly do suspect your interior protectants, then let them dry with the doors open or windows down, or try a different kind that flashes faster.