Google has announced that it will begin cracking down on “intrusive interstitials” on January 10, 2017, because this type of ad “can be problematic on mobile devices where screens are often smaller.”
Google will be potentially penalizing — i.e., lowering the rankings — of these web pages. Google said “pages where content is not easily accessible to a user on the transition from the mobile search results may not rank as highly.”
Google explained which types of interstitials are going to be problematic, including:
Showing a popup that covers the main content, either immediately after the user navigates to a page from the search results, or while they are looking through the page.
Displaying a standalone interstitial that the user has to dismiss before accessing the main content.
Using a layout where the above-the-fold portion of the page appears similar to a standalone interstitial, but the original content has been inlined underneath the fold.
Here is a diagram from Google to