Look at any Impreza from the 1990’s and there is probably rust behind the rear wheels, along the bottom of the doors, and assorted little mystery spots. Here I have cut out a section of rust_rot. E noticed it when a fin of metal protruded after she power washed her car.
Here is a chunk of the rusty mess that was cut away.
The first image shows the aluminum screening fit to the hole, with straws behind it to pull water from the wheel well. This is after bondo and grinding and smoothing the bondo, then prepping for paint.
Better than a big rusty hole.
Triage always leaves fine scarring.
The underside of the passenger door was blowing out as well.
It was just a matter of grinding back to clean metal, base coat, and topcoat. easy.
This is a spot that returned, so redo grind/paint.
You have to get pretty close to see it, and know where to look.