Web Messaging API 429s during high-concurrency load test

Quick question about handling rate limits on digital channels. Running JMeter 5.6.2 against Genesys Cloud BYOC Edge 24.1.0 (Asia/Singapore). Trying to simulate 100 concurrent web chat sessions via POST /api/v2/conversations/messages.

  1. Authenticate with OAuth2
  2. Loop 50 threads hitting the message endpoint
  3. Observe immediate 429 Too Many Requests

Docs are vague on digital channel throughput. Is this a known limit for this tier?