title: Datadog: enabling RUM allowedTracingOrigins raises CORS errors
body: <p>I tried to connect <a href="https://docs.datadoghq.com/real_user_monitoring/connect_rum_and_traces/?tab=browserrum" rel="nofollow noreferrer">RUM with backend traces</a>. In react SPA application I setup a datadog-rum and enabled allowedTracingOrigins option for it, after that our fetch and xhr requests to API started to fail.</p>
  <p>How to connect RUM and backend traces properly?</p>