title: Firebase shows authenticated users even though users where deleted
body: <p>I am using firebase admin sdk with nodejs to manage users accounts, specifically, migrating from one firebase to another.
  Though the migration ran well, I noticed a problem when I decided to delete all the users that were migrated and run the migration again. </p>
  
  <p><a href="https://i.stack.imgur.com/GnGLh.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GnGLh.png" alt="Firebase showing there still are users even though no one is listed"></a></p>
  
  <p>This is the code that migrates auth users: </p>
  
  <pre><code>async saveAuthUsers(authUsers) {
      try {
        const hash = {
          hash: {
            algorithm: 'STANDARD_SCRYPT',
            memoryCost: 1024,
            parallelization: 16,
            blockSize: 8,
            derivedKeyLength: 64
          }
        };
        const userImportResult = await this.firebaseTo.auth().importUsers(authUsers, hash);
        // failed auth users
        if (userImportResult.failureCount) {
          userImportResult.errors.forEach((indexedError) =&gt; {
            console.log('User: ' + authUsers[indexedError.index].uid + ' with email: ' + authUsers[indexedError.index].email + ' failed to import ', indexedError.error);
          });
        }
  
        authUsers.forEach((authUser) =&gt; {
          console.log(`Current migrated user uid: ${authUser.uid} email: ${authUser.email}`);
  
        });
      } catch (error) {
        console.log(error);
      }
    }
  
  </code></pre>
  
  <p>Is there any reason why this could happen?</p>