Drain holes blockage
Make sure to check any drip holes in your doors and rockers to make sure they are not plugged with the rustproofing compound. I worked many years at dealerships and we often saw pooling in doors after rustproofing. I remember sticking a small screwdriver in a drain hole and watching about a liter (quart) of water run out onto the floor.
People sometimes think that the window belt moldings seal water - they cannot possibly do that. So there is always water running on the inside of doors - hence the vapor barrier.
I could rant now about "paint sealant." The invisible forcefield that protected your car from rock chips and had a lifetime warranty. Except that if you did not have it inspected every year the warranty was void. Oh, I guess I just did!