It usually means someone has your password. Here's what to do.
How it normally works. When you sign in to your work account, you confirm it's you on your phone, using Microsoft Authenticator or Duo. With Microsoft Authenticator, you type the number shown on your sign-in screen into the app. That way, only a sign-in you started can be approved.
When it's not you. A request you didn't start usually means someone has your password and is trying to sign in. Approving it would let them in.
What it's not. A request you started yourself on a new computer or browser is normal. If you're not sure whether you started it, deny it and sign in again.
Got a new phone? Move your authenticator before you wipe or trade in the old one. Contact us and we'll help you set it up.