Constant unsolicited Microsoft Authenticator "New sign-in request" notifications despite multiple password changes

I keep receiving repeated "TIME SENSITIVE New sign-in request for your Microsoft..." notifications from the Microsoft Authenticator app on my iPhone throughout the day (multiple times in the morning and afternoon). I am not trying to sign in to any Microsoft service or account when these appear.

I have already changed my Microsoft account password several times, but the notifications continue without interruption. I never approve any of these requests — I always deny them immediately.

This is very disruptive.

What is the proper way to permanently stop these unsolicited sign-in requests while fully securing the account?

Account type: personal Microsoft account

MFA method: Microsoft Authenticator

Device: iPhone