I have never noticed more users than the title of the message that notified me said. The message says 1 and I only found 1.
But even without Data Explorer, you can efficiently find unapproved users. You can export your user directory using the button at the top right of /admin/users
and open that with whatever you prefer to check for users where approved is false. I used Excel, and you can see that there is really only one user:
