I would think so. I had to get a new faraday bag after a few uses. I put my key in the bag when I go Scuba diving and need to lock my key in the truck, one day it just stopped working. I think if the bag gets a tear or a gap is created in the blocking material from use, a signal will get through.
I would agree, energizing a circuit with no load is easier on the relay contacts vs with a load. Same with de-energizing a relay, so much easier on the contacts when no load like Christmas lights are present (no Christmas pun intended).
Sorry you couldn't find a part number. I had some time this morning so I modeled one up for you so that it could be 3D printed.
Here's the link to my Thingiverse upload.
Ford Maverick Bed Rail End Cap