UXP Webview - Firebase "Login with Google" does not work

Hi There, 

We are building a POC for a GEOlayers UXP plugin. The setup is very simple atm:

• UXP Plugin that displays a webview of https://editor.geolayers.app
  

   

Our webapp on editor.geolayers.app uses firebase auth. It works fine across all browsers. However inside a UXP webview the google sign in breaks: 

Has anyone an idea what's wrong here? I'd love to know what the underlying chromium is doing different that leads to the error. And is there a workaround?

I have attached a screedcast and the UXP manifest.

Thanks for any advice on this!

Best regards,

Markus