Conversation API 429 on single thread

Does anyone understand why the v2/conversations/calls API returns 429 Too Many Requests with a single JMeter thread?

Genesys Cloud BYOC Edge 24.1.0
Asia/Singapore
JMeter 5.6.2
1 thread, 100ms delay
Retrying every 1s
Still getting rate limited immediately
Is there a hidden per-org limit?