Account compromise has two halves, and Clicc watches both.
Pending access invite - the earliest signal, before access even exists.
New user / access change - a person gains access, or an admin role appears.
New manager link - an unfamiliar MCC gains bulk control.
All three run every 5 minutes against your trusted baseline.
Critical setting change - budgets jacked up, targets shifted, campaigns paused.
Runaway spend - the money actually leaving.
Conversion tracking broke - tracking tampered with to hide the damage.