With them switching to water based clear, this is more of a QE failure than a QA issue. QE needs to fix this and create new QA processes to detect issues before the playfields are populated.
This does kind of remind me of the RoHS cluster F that happened 15 years ago. The new environmentally friendly lead free solder promised to be just as good as the old stuff, but soon every new TV or stereo I bought was failing within a year or two. Previously TVs and receivers were reliable as hell for many years. I bought a Sony AVR in 2004 along with a 32 inch TV. Both of them were nothing but trouble. Every time something would fail, I'd open it up and flow some leaded solder onto components until it started working again. One thing for sure, Sony never had a mea culpa or gave me new boards to replace the failed boards. ASUS never gave me new motherboards to replace the ones with bad capacitors either. Eventually RoHS worked out fine, but initially it sure filled a lot of landfills with electronics. I suspect that playfield manufacturers are scrambling right now to find what works and purge supplies of the clear that doesn't work.
Personally I would be happy with Stern selling me a new playfield at their cost because all I have is pooling and it is not bad at all. They should send corrected playfields for free in more extreme cases that include cracking.