Valve installed it on a test server beta version of the new interface, Panorama UI for the game Counter-Strike: Global Offensive. According to the developers, this is the biggest update the appearance and functions of the game since its release in 2012.
Changes in the update have affected the main menu, leaderboards, inventory, friends list, lobby, appeared news and animations for weapons, and so on.
Since this is a test release of the Panorama UI interface, it has limited functionality. At the moment, for players only practice with bots or play with friends in offline mode. The timing of the launch of the new interface on the main server yet to be announced.