Core user activity drop
Daily or weekly active users fall 30%+ over 60 days among the account's core user cohort. Usage is the ground truth — everything else is commentary.
Detection logic
Define the core cohort (users active 3+ days/week at peak); track cohort DAU/WAU vs its own peak. Flag sustained 30%+ declines over 60 days.
When it lies to you
Seasonality, holidays, and industry cycles move usage without meaning. Compare against the same period last year, not just last month.