Smelly mold inside doors from Woolwax?

F.Y.I.
I rustproofed my 2020 Tundra Crewmax about a year ago with Woolwax.
Recently, I started smelling a strong mildew odor in my truck, it took me a while to figure out where it was coming from. At first I thought the carpet got wet but later discovered it was coming from inside the doors.
I had to remove the door panels and I could see and smell the mold at the bottom of the door. I am removing the Woolwax with a spray bottle filled with warm water. The drain holes were not plugged, but it must have held enough moisture to create the mold.
Has anyone else had this problem?

 

Why would an undercoating be sprayed inside of your door?

 

I live in the rust belt where they apply salt to the roads in the winter. Truck fenders, rockers and doors are known to rust severly if not rustproofed.