here鈥檚 what gemini-3.1-pro says about the deploy script
If you deploy your app using --entrypoint-object=root_agent (or app), Vertex AI serves the ADK agent directly. Because the ADK Agent class doesn't use your custom set_up() method, Vertex AI silently skips it during container initialization. Your agent responds to queries perfectly, but the OpenTelemetry provider is never initialized.