Screen Recording API 503 during JMeter ramp

Does anyone understand why the recording storage endpoint fails under load?

Testing on Genesys Cloud US1.

JMeter 5.6 with 30 concurrent threads.

Endpoint: /api/v2/recording/recordings.

Getting 503 Service Unavailable after 10 seconds.

Architect flow is simple IVR.

Is this a rate limit or capacity issue?