We all know the annoying popups that get in the way of the content you are trying to view and then struggle to get rid of as they have minute close buttons. It seems Google also finds this annoying and is set to penalise sites that use them on mobile devices.
The popups are now a ranking signal for SEO like HTTPS became a ranking signal in 2014 when they started to push the web in to being encrypted. Google said they have seen a marked increase in the number of intrusive popups which cover the page content, while still making the content easily visible to Google, so the decision has been made to combat this.
Good news for everyone browsing sites on mobile devices, bad news for sites that try to force you to click on a advert!