Discovered this after couple of hours of being confused.
In normal chats, Claude desktop doesnt even display API Error: 529. It only does so in Cowork tasks. The regular chat just does an infinite "Clauding" animation.
Contrast with Claude Government with all green 100% uptime. So either no one is using it or the people within Anthropic running that one have different priorities.
Same here, our Claude API calls started throwing 529s this morning. Added a simple retry-with-backoff and it recovered fine once the incident cleared, but definitely caught us off guard.