A "Phone Pickup" is recorded each time your device's screen turns on, whether you unlock it or just view notifications on the lock screen.

This count starts fresh daily at 12:00 AM, aligning with the beginning of a new day. So, any interaction with your device after midnight contributes to your daily pickup count.

This is how Apple tracks pickups and it is consistent with industry standard measurements.

If you want to reduce unintended pickups, you might to enable "Do Not Disturb" or "Focus Mode".