Our current pop script from our network has yet to be hit with a warning on publisher sites. I'm not saying that it won't. We have moved forward with testing some new options just in case it does.
We did get hit by Google on our test site that we had our old pop script on. Based on the video they sent us the person that was clicking around had to be in what we considered a tier 3 country based on the ad that popped for them (they could have been using a VPN as well). Also when google blocked all the ads on the site, a simple Adblock trick got around that. After that we ended up removing all the ads and got the site cleared by Google. Using the old script we limited that to exclude chrome and we are testing a new ad type there for chrome only.
My opinion is I don't like what Google is doing now. It was ok at first to make sure pops were not hindering the user's experience, but now it feels they are trying to control too much. Also this better ads coalition
https://www.betterads.org seems to be backed by them and not a real independent board. But it has gotten us to think about new ad formats to offer that are on the same level as popunders.