Google ranks sites based on hundreds of signals like how useful they are, how safe they are, and more. Google has also been working hard to push for more useful sites, ranking sites lower if they don’t have mobile sites.
Google’s next step is to change rankings based on intrusive pop-up ads. Starting January 10, 2017, Google will rank sites lower if they have intrusive pop-ups that degrade the user experience. This doesn’t include those that warn about cookies, ask for your age, or cover only part of the screen. The rules are open to interpretation.
Overall, this is a good move by Google to make the user experience better on mobile. I don’t think anyone likes pop-up ads, though ads are an integral part of many sites. Hopefully this will encourage sites to improve their ad experience, though since this is only one of hundreds of signals, this may not affect big sites.