Most sites get more mobile traffic than desktop. And as you may know, Google is starting to use it's Mobile First Index for searches. Bottom line: mobile is more important than ever, and that's not going to change anytime soon.
We're using Google Pagespeed to calculate the speed of your pages. This tool reports a score for your pagespeed on mobile, and one for desktop.
Up until now, we were using the desktop score in our reporting. Given the increasing importance of mobile, we've now changed that to mobile. It makes sense, because more and more people will experience the mobile version of your website. You'd better make sure that one is fast!
As a result, you may see a slight change in the Pagespeed score. If your page is really slow on mobile, your overall page score will decline. A good reason to start fixing it!
I believe this way we're prepared for the Mobile First Index.