Don't you love that Microsoft Entra ID now insists you install Authenticator even if your primary login method is Yubikey and the URL is, literally, an "upsell"?

hxxps://mysignins.microsoft.com/register?requirement=AppUpsell

and it won't let me log in unless I install it…

@cynicalsecurity You can log in with Yubikeys to Entra accounts???
@diagprov yes, of course.
@cynicalsecurity @diagprov Yup, I worked there and we all had 100% official retail yubikeys for login (or multiple). And every time I setup a new machine I needed it because oobe demands the key during setup.