Data Action Timeout in Architect Flow During Load Test

I’m completely stumped as to why the custom Data Action fails only when simulating 200 concurrent users. The flow works perfectly at 50 TPS. The integration with our legacy CRM via REST appears stable, but Genesys Cloud returns a timeout. This happens specifically on the POST request to the external endpoint. Is there a hidden rate limit or timeout setting for Data Actions that I am missing?

408 Request Timeout: The server did not receive a complete request message within the time that it was prepared to wait.