Your question is Virtual Card Number Case. 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).
Case on virtual card numbers: discuss the scenario, then look at some code and fix it.
Asked in the power_day_case stage. Treat this as a practical exercise: clarify the expected behavior, inspect the supplied implementation, explain the defect, make the smallest safe change, and validate it with relevant tests. Be prepared to discuss assumptions, edge cases, and how you would coordinate review and rollout.