I have a little plastic piece that was with my inner door latch hardware. I am not finding it in any pictures from disassembly. For some reason it seems it was related to the inner door release handle, but am not quite recalling.
It goes on top of that mechanism to keep the water off of it. It was needed when thees cars sat outside daily. Is this a garage kept,car now or an outside Car? That will tell you if you need it.
It clips into the door before you install the mechanism. It doesn’t go on the cardboard door panel.