Verifiying Embed URL as Valid or Unauthenticated Programmatically

I have a Metabase embedded URL. I am generating a URL with valid JWT string. Now when I try using this embedded string with JWT token also it gives status code 200 in WebClient and without JWT also gives 200.

Not sure where and what we need to inspect in the content to discriminate between a valid response and any error message.

When I try to view both the URLs in web browser, the one with JWT showed the dashboard and the other one showed a Not Found image.

My requirement is to detect the situation through WebClient (C#)