Two months ago, Google warned us that app interstitials may lead to a penalty, if they take up too much of the page, covering most of the content. Well, yesterday, November 2nd, that penalty went live into the overall mobile friendly algorithm.

Google posted the news yesterday afternoon on Google+ saying:

No one should be surprised by this but I have yet to see people complaining in the forums that their sites were hit by this penalty.

Forum discussion at Google+.