I had an interesting situation a while back where my then corporate login appeared amongst my personal Microsoft accounts as possible options to log into upon installing Microsoft office iOS apps on a personal device - given that org’s corporate policies don’t allow logging in that way I could fathom how it was appearing (it might have been linked to once trying to use Authenticator for 2FA) but it was a bit odd seeing it as a prompt on downloading a fresh iOS Excel. It seems to have stopped now but was a bit odd!