- Anthropic secretly inserted a tracker in Claude Code to monitor Chinese users, using prompt steganography to hide code that flagged timezone, proxy, and potential connections to Chinese AI labs.
- The tracker, added as an 'experiment' in March, was intended to prevent account abuse from unauthorized resellers and protect against distillation attacks, with resellers offering cheap subscriptions.
- Anthropic quickly removed the tracker after exposure by a security researcher, who condemned it as a 'serious breach of user trust,' while privacy advocates criticized the surveillance despite Anthropic previously refusing US government surveillance requests.