The pop bumper rings were originally floating pieces of mylar. They allow dirt to get trapped under them where it grinds into the playfield. Once you take the pops apart, you will likely find that's not adhesive but whatever ink is left clinging to the underside (very common on Gottlieb games).

Replace with ones that are sticky after you clean the area up.

Unless you do a full restore on the PF it would always look like a PF that you touched up. I'd leave it as is.

Pinball Resource sells the pop bumper mylar and likely most other suppliers do as well. The pieces of mylar on your playfield protecting wear used to come with many games to put in front of the slings as that's another high wear area and lots of operators had them in their stashes to 'fix' worn playfields (cleaning and waxing would be asking too much of route techs at the time... lucky to get a dirty rag over the PF every so often. Arcades were much better, the supercade by me growing up the attendant would clean and wax on average one game a day, they had about 30 pins. Video game maintenance was much easier, windex and paper towel.)