Inside the trim panel were sheets of "waterproof" paper that were supposed to divert water away from the trim panel and into the bottom of the door where it could drain. These didn't have a very long life. I'm not aware of anyone who repops these. Eventually most manufacturers starting using plastic sheeting instead of paper. You can use any sheet plastic to make replacements. Just make sure the bottom is tucked into the slot so any water will be diverted into the bottom of the door.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.