admin created outside site but wasn’t?

I’m getting ‘An admin user with the username #### was created outside of WordPress.’

Now this was critical when hackers started doing it but now it’s doing it even when I created a new user from within wordpress to replace all our old (compromised) user names.

Mind you I’m also concerned it lists 3 admin users where there are only 1 (shown on both backend and database)

But the false alert is confusing things a bit. Is there any way to prevent it?