Google Picker API returns 403

We have an integration in our app that allows the user the select a folder from their Google Drive using the Google Picker.

All was going well until yesterday and now when trying to open the picker, the app completes oAuth but then returns with 403

This is a bit strange, I confirmed all keys, clientId, and JS origins and nothing has changed in the app or in the cloud console.

I did however notice that the URL contains relayURL and is set to <protocol>://<domain>/favicon.ico that is very strange. I used filePicker.setRelayUrl('<domain>') ** without and it works, except now the callback is not fired and there are no console errors or logs.

Just wondering if there was a change in Google's api.js.

Here is the sample code for building the picker. I am using Angular 8.

 //Create the google picker
 this.picker = new google.picker.PickerBuilder()
               .setTitle(`Please select a folder to sync`)
               .enableFeature(google.picker.Feature.NAV_HIDDEN)
               .enableFeature(google.picker.Feature.SUPPORT_DRIVES)
               .setAppId(this.appId)
               .setOAuthToken(this.oauthToken)
               .addView(foldersView)
               .setDeveloperKey(this.developerKey)
               .setOrigin(window.location.protocol + '//' + window.location.host)
               .setRelayUrl(window.location.host)
               .setCallback(this._pickerCallback)
               .build();

  this.picker.setVisible(true);

  private _pickerCallback = (data): void => {
        
        // User has closed the picker
        if (data.action == google.picker.Action.CANCEL) {
            // Do comething when user clicks cancel
        }
        else if (data.action == google.picker.Action.PICKED) {
          // Do something when picked
        }
   }