Your question is QA Without Documentation. 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 managed quality assurance when documentation was missing. Explain how you established reliable requirements, identified risks, validated the data or process, and aligned stakeholders despite the ambiguity. Focus on your specific actions, the evidence you used, the outcome, and what you changed afterward.