Step 7 of their instructions:
“If all moisture has not been evacuated/squeegeed out from under film then some fogginess of the film will occur. This is completely normal. The film is breathable and porous…[continued]…the film is self-annealing, so that hole will eventually heal up.”
If it’s breathable and porous, would you not think that water MAY find it’s way in? Even if it didn’t, I think the issue is that it’s not porous enough, causing an issue with heat dissipation. Head lights don’t get anywhere near as hot as fog lights.