Your question is Debug Validation to Production Gap. 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).
You've shipped a model that looked strong in validation, but it is underperforming after deployment. You need to figure out why the offline results did not hold up in the real world.
Tell me about a time your model performed well in validation but failed in deployment. How did you debug it?