User's name
Returns the name of the current signed-in user (Name value), if provided by the authentication provider, or blank.
Note: This function is deprecated. Many authentication providers no longer pass the users name so this function will often return blank. We recommend using the USEREMAIL() function when you need to identify a user.
Syntax
USERNAME()
Notes
The user's name is obtained from the service through which the user signs in to the app. If the user is not signed in, the name is not available. Even for signed-in users, not all authentication providers make the user's name available.