My 2 cents based on the new Stern games I've run over the last few years: This is simply due to assembly too soon.

I have two games on location right now that have wrinkling around posts, GotG Pro and BKSoR Pro. GotG only has wrinkling at several posts, no chipping. BKSoR has wrinkling at several posts and chipping at the lower sling posts. Everything else about the playfields is fine.

I have had two other recent Sterns that have no issues at all, Deadpool Premium and Munsters Premium. No wrinkling, no issues at all with the clear.

So what's the difference between the two games with issues and the two without? The two with issues are Pros that were assembled early in the game's run. The premiums were assembled later since they are produced after Pros. It is likely that their playfields were produced around the same time as the pros, but they sat and had more time to cure. By the time they reach assembly they had hardened and didn't wrinkle when posts were tightened.

I think if this was an adhesion issue, clearcoat issue itself, or issue with the underlying artwork, I'd be seeing other problems and problems showing up after several months. I'm not. It is simply due to posts being tightened down when the cure is still soft. It later chips after the cure hardens because it is thick and can't flex enough. The vibration from the slings and flippers makes this especially evident and is why we see chipping so soon at those posts.