this crazy that in this day these companies are having issues, I got a Batman 66 late last year and returned it back to the distributor after only 6 games when I noticed very similar lifting around various posts.
Maybe Stern and JJP need to machine a small step in the top of the playfield for a washer to sit in so the post sits a fraction above the playfield surface to get around this bubbling as well as look at there clear mixture as something drastic has changed of late. Once the washer is tightened down it should not affect the actual playfield, but putting a washer on the playfield surface is just a bandaid fix and widens the problem.
I think these companies are going for a eco friendly water based clear which is quicker and cheaper to apply compared to a urethane clear coat. Here are some comments from the auto industry - on acrylic versus urethane
and this one talks of arcylic clears chipping
then when you read into it the acrylic clears need a suitable base to bite in so a printed playfield artwork may have reactions to an acrylic clear.