Well, AFAIK, the so-called Cloud cameras that don't require (nor support) an NVR must be allowed to call-home, whether for setup or regular functioning. They don't do anything inside the LAN. That way they can be easily watched from anywhere, as they don't require open ports on the router, and can work even behind CGNAT. The obvious downside is the video is sent to the company's servers, and given how cheap the device is and how expensive storing and streaming video is, you can bet they're monetizing it somehow...