Google have of plenty of notice that yesterday, January 10th, the Google mobile intrusive interstitials penalty would launch on January 10, 2017.
Google's Gary Illyes and John Mueller both confirmed it is indeed starting to roll out.
This only impacts interstitials that are present when someone clicks from Google's mobile search to your web page. It doesn't currently impact desktop or does it impact what you do from within your site.
Here are examples of bad mobile interstitials:
Did you notice any site getting hit by this?
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