We have a playfield protector and a full set of Cliffys fitted on every machine we own. They are a pain to put on and a little painful to look after as you have to vacuum the machine every time you clean it to stop the dirt and dust getting under the protector. We have fitted playfield protector to 3 NIB Sterns and each one has the issue in your photos. Ours are not as bad as that as we ask our distro not to wax or spay anything on the playfield before we get it. I believe this is the wax or polish applied to the playfield at the factory. It is extremely hard to get off. We do our best to get as much off as we can with novus no1 before putting the protector on. Once we start playing the machine, we have a long piece of flexible plastic and push a microfiber rag in between the playfield and the playfield protector until the wax is gone. Process is quick but It takes a while before the wax is gone.
Up side is ball scratches the shit out of the protector not PF, no ball track marks on PF, much less dimpling, no stuffing around with mylar, no mushrooming of magnets, The list goes on and on. You can still Novus no 1 & 2 the playfield protector and machine plays like lightening. Machines are very easy to sell with a nice minty playfield. Surprisingly, most people ask us to take the protector off before giving them the machine.