title: Listen for changes if anonymous firebase account is upgraded from server side
body: <p>How do I listen for anonymous account changes? I have noticed, that the <code>onAuthStateChanged</code> won't change if I &quot;upgrade&quot; the user from server side.</p>
  <pre><code>// server side &quot;upgrade&quot;
  const authUser = await updateUser(uid, {
    email, emailVerified: true, password, displayName: `${firstName} ${lastName}`, disabled: false
  });
  (...)
  return await auth.createCustomToken(uid), 
  </code></pre>
  <p>My checkout flow:</p>
  <ol>
  <li>User finished the checkout with a message to check his mails (gets an anonymous user id)</li>
  <li>Receives an email to create his account</li>
  <li>Most likely opens the email on mobile or in another tab / browser</li>
  <li>Creates the account with username/password and receives a token</li>
  <li>Old-Tab content won't change</li>
  </ol>
  <p>My problem is that if the user confirms his account, it will most likely happen in a new tab or on another device and leaves the old tab in an outdated state. I'd like to update that tab as well with a welcome message.</p>