Anthropic reports it also paused "high-risk" RL runs for a few weeks after incidents on July 30 [1]. But it doesn't seem like a serious effort at a coordinated "pacing". Perhaps they are afraid of antitrust regulation [2].
[1]: https://www.anthropic.com/news/improving-alignment-security-...
[2]: https://x.com/DaveRBanerjee/status/2094168663314387319