Would it be possible to get a new lens or one from a junkyard?
Looks like an old “Dymo” (trademark; maybe a knock-off) label. I Googled for “remove dymo label tape” and came up with a bunch of discouraging links. Here’s one:
https://www.pentaxforums.com/forums/38-photographic-technique/103470-removing-those-old-school-labels-your-gear.html
Yeah, that’s what I said earlier. Dunno what specific plastic it’s made of though.