title: window.gapi.auth2.getAuthInstance() is empty on IOS 14.2
body: <p>setup login page</p>
  <pre><code>this.auth2 = window.gapi.auth2
  .init({
  client_id: process.env.GOOGLE_ID,
  ux_mode: 'redirect',
  redirect_uri: process.env.GOOGLE_LOGIN_REDIRECT, // https://domain/callback
  scope: 'profile email',
  prompt: 'select_account',
  })
  .then(() =&gt; {
  let googleAuth = window.gapi.auth2.getAuthInstance();
  googleAuth.signIn()
  });
  </code></pre>
  <p>in callback page
  <code>window.gapi.auth2.getAuthInstance().currentUser.get().getAuthResponse()</code> is empty only in IOS 14.2 but another version is work and android is work also.</p>