String 'newusernewpasswordtext' in lang/en/moodle.php references $a->firstname.  This string is used for sending new password emails out to new users in lib/moodlelib.php at \setnew_password_and_mail.

The issue is that the logic is setting firstname to the user's fullname instead of their first name.

To reproduce the issue, create new user ensuring that 'Generate password and notify user' is checked.  Then, verify the contents of the email.