Your question is Observability for Reactive APIs. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Explain how you would monitor and troubleshoot a WebFlux-based backend using Prometheus, Grafana, and Datadog, including how you would think about concurrency and resource usage.