Once an attacker has a working password, the only thing between them and the account is the second factor. MFA-fatigue attacks skip trying to break it: they trigger approval prompt after approval prompt, often late at night, betting the employee taps “approve” just to make the buzzing stop.
The defence is a habit, not a tool
The rule to teach is simple: an approval prompt you did not start is an alarm, not an annoyance. Deny it, then report it. A flood of prompts means someone already has the password, which is exactly the moment to tell IT, not to tap through.