Diagnose drop in shopper accepted orders

Instacart notices a sudden issue: on Sunday afternoon, the number of orders accepted by shoppers drops by about 2/3 compared to the usual baseline.

As the on-call / bar-raiser-style case interviewer, you need to diagnose the problem.

1. Clarify the metric: what exactly does “orders accepted” mean, and what denominator(s) matter?
2. Propose a structured root-cause tree from three perspectives: (a) shopper supply, (b) customer demand, (c) merchant/store operations or platform systems.
3. List the key metrics and slices you would check first (at least 10), and what patterns would support/refute each hypothesis.
4. Describe how you’d determine whether this is a real behavioral change vs a logging/measurement issue.
5. Propose immediate mitigations and longer-term fixes, including at least one experiment or rollout plan to prevent recurrence.