Users of audio app Clubhouse expressed frustration and fears of government surveillance, but little surprise, after it was blocked in China following a short period of rare open dialogue on sensitive topics.
The move on Monday evening, reported by users and an anti-censorship watchdog, ended a brief window when mainland Chinese users joined people in Taiwan, Hong Kong, and the Uighur diaspora to discuss topics often censored in China, without having to use virtual private network (VPN) software to bypass internet controls.
Many new users from mainland China had talked about topics including Xinjiang detention camps, Taiwan independence and Hong Kong's National Security Law that would normally be swiftly censored on Chinese social media. The discussions attracted participants such as Chinese artist and dissident Ai Weiwei, who now lives in the West.
Given China's tight controls on online discussion, many users said it was just a matter of time until it was blocked.
"After seeing people discuss so many political issues here in previous days, I knew right away that Clubhouse will be walled, and so it was," one user said on Monday.
Anti-censorship activist website GreatFire.org said on Twitter late on Monday that the app had been blocked for usersin China at around 7 p.m. Beijing time (1100 GMT).
Clubhouse and the Cyberspace Administration of China did not immediately respond to requests for comment.
"How can we speak about reunification if we can't hear what youths from Taiwan and Hong Kong are saying, and they can't hear our perspectives?" said a user in a popular room where people from mainland China, Taiwan and Hong Kong can speak for two minutes on any topic.
China regards democratic Taiwan as one of its provinces and has not renounced the use of force to bring about reunification.
Some users mourned the end of a brief window of free expression, while others voiced concern over user privacy and the possibility of authorities listening in on discussions.
"I advise everyone not to use your real photo as your profile picture, and not to link your Clubhouse account to your Twitter," one user said. Another advised people not to discuss which VPN they were now using to access the app.
Foreign social media sites such as Twitter and Facebook are blocked in China and are only accessible using a VPN.
"Now that Clubhouse is blocked, we are back to parallel internet universes," Yaqiu Wang, a researcher at Human Rights Watch, said on the organisation's website.
Many disagreements had emerged from discussions, she said.
"But people on Clubhouse appeared to truly try and put themselves in the shoes of others. It was wonderful to see a unifying internet in which Chinese-speakers from around the world communicated with each other in one shared online space."
(Reporting by Yew Lun Tian and Gabriel Crossley; editing by Richard Pullin)