Your question is Debugging Production Issues. 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).
Describe your process for debugging a production-level issue.
Explain how you establish impact, collect evidence, narrow the fault domain, and validate both the fix and the absence of regressions. Include how you distinguish symptoms from root cause, communicate during the incident, and decide whether to roll back, mitigate, or deploy a fix.