So my company decided to migrate office suite and email etc to Microsoft365. Whatever. But for 2FA login they decided to disable the option to choose "any authenticator" and force Microsoft Authenticator on the (private) phones of both employees and volunteers. Is there any valid reason why they would do this, like it's demonstrably safer? Or is this a battle I can pick to shield myself a little from MS?
You can use Aegis and/or Yubico Authenticator instead, that's what I do.
In my company at least, Aegis works for the first few logins, but it will keep nagging you have to switch to Microsoft's authenticator and you're locked out after a while.
How did know you're not using the MS Authenticator? Does the MS app phone home what logins your using?
Apparently MS uses a "proprietary PhoneFactor 2FA solution" that Aegis doesn't support.