It looks like several Steam Community features and services have been blocked in China.
As reported by ValveTime, that includes the Steam Community page and everything it encompasses -- such as forums, guides, achievements, badges, game hubs, and groups.
The Steam Store and Steam itself are still open for business, so Chinese users will still be able to play and buy new games, but it looks like it'll be a rather lonesome experience from now on.
Meanwhile, some Reddit users have suggested that friends lists and chats are still available, but it's difficult to verify those claims from outside the self-styled People's Republic.
It's sorry state of affairs, but it's hardly surprising given China's history of clamping down on foreign products.
Earlier this year, the Chinese government reportedly implemented a full ban on the release of games developed in South Korea as a political warning.
Prior to that, it blocked Gears of War 4 from the Windows 10 store for being too violent, showing it isn't afraid to chastise big name players like Microsoft.