Earlier quoted context omitted.
Am I the only one that is not worried at all about the camera and super concerned about microphones ? The camera may see me staring into the screen, woo hoo. The microphones will hear everything I discuss, incl. confidential information. There is no physical microphone cover there, is it ?
And the true or not Google or other apps listening then you see ads based on that conversation. I think it's true since far too many times obscure things I've spoken about appear in ads soon after the conversation. So yes I'd say a mic blocking feature you can confirm is working, blocking, is needed.
For this to work hangouts.google.com had to not include the HTTP header to block iframing but thankfully if you make up a URL the 404 page served on that domain does not include that http header.