Your question is Critical Defect Before Launch. 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).
What would you do if you found a critical defect right before a production launch?
Describe how you would assess severity, determine whether to proceed, delay, roll back, or reduce scope, and communicate the decision. Include your validation, escalation, mitigation, and post-launch monitoring approach.