As far as new features, there is so much that it could have easily been v 3.5! But we decided that 3.5 will be where we update all blocks of the platform in one release. So left it for sometimes later in 2020.
Version 3.1 does not have any new visible things in the Progressive Web Apps department. Under the hood though, a different story. (1) we greatly improved on how our dynamic app data is updated on a background, (2) we increased speed of app's work so much, that we had to slow it back down by 0.25 seconds per each user action, to make sure a button press is visible to a user.
Anyway, our goal is to constantly make PWAs better and faster and easier to make from start to end. So, here is Mobsted version 3.1.