How do you handle "ghost churn" where users stop logging in weeks before canceling?

I used to only focus on the day a user clicked "Cancel Subscription." But when looking at usage metrics, the truth was much more uncomfortable.

The hardest realization was that users actually churned 30 to 40 days before making it official. They simply drifted away, stopped opening the app, and left the subscription running until the credit card statement reminded them.

For founders tracking active usage: how do you build early warning trigger or re engagement loops to catch drifting users before they reach the point of cancellation?