Your question is Owning a Critical Defect End-to-End. 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).
Tell me about a time you found a high-severity defect late in the release cycle. Walk me through how you drove it through the defect life cycle—from discovery and triage to verification and closure—and how you kept the right people aligned along the way.