Your question is Debugging a Critical Production Issue. 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 a time you had to debug a critical production issue under pressure. Explain the incident's impact, how you prioritized investigation and mitigation, how you coordinated with others, and what you did to prevent recurrence. Focus on your specific actions, decisions, communication, and measurable outcome.