The new look YouTube PiP (Picture in Picture feature is now rolling out broadly to everyone this morning. The new design of the PiP is aimed at providing a bit more information about the video you have in the smaller view window such as the name of the video, not just a thumbnail of the video itself.
Now when you are viewing a video on YouTube and swipe down to put it into the PiP view, you will not only see the video but will see the title of the video as well as the creator of the content in a white panel next to it.
The only downside to this change is that the video itself when you move into PiP is considerably smaller than it was prior to the change.
The new PiP changes are just the latest in a series of small updates that YouTube has been making to the Android app for the service all in an effort to bring a more unified experience across all platforms.
From a user perspective, there is nothing that you need to do. So long as you have the latest version of the YouTube app on your phone, this new PiP view will roll out to you. It is a cloud-side change and just a matter of when your Google account gets updated with the new feature.