Update 1: 2018/02/07 5:31pm PST
Content is now actually appearing in the new My notifications section on the Play Store.
It appears that the Play Store team is testing another new feature in the Android app, though you may like this one more than the new tab bar that's been rolling out to more and more devices. In the side menu of the Play Store, some users are seeing a new Notifications section, right below My Apps & games.Read More
[Update: Now being populated] Google Play Store shows a new Notifications section for some users was written by the awesome team at Android Police.