For a brief time before Beijing banned the audio chat app Clubhouse, tech-savvy Chinese joined global discussions on taboo topics — Beijing’s placement of Uighurs in concentration camps in Xinjiang, Hong Kong’s pro-democracy movement and the 1989 Tiananmen Square protests — absorbing perspectives and information far outside the lines drawn by the Communist Party.

Unlike Twitter posts, there was no public record of the app’s audio messages, which may complicate official monitoring efforts, according to