It was probably a sample playfield made without clearcoat or sealercoat and slipped into the production playfields by accident.

I have.

Any sys11 that did not get the factory Mylar looked like that in just a few months.

Any B/W game you see today has already had all the factory mistakes culled from the pack.

If a B/W playfield was a sample and somehow found it's way into a production game, it got destroyed 20 years ago when it went on route. It would not have lasted long enough for anyone to suddenly see it happen today.

Williams would ship a populated replacement playfield in a wooden crate to the local distributor. They would never ship direct to the operator.

Stern does not do their own clearcoats.

The playfields are still done by CCC, just like B/W were.