Over the weekend I got Pi-hole up and running (first time user), and it sure is eye-opening seeing what your devices are up to.
The screenshot that's all red, for example, is my Samsung smart TV, which is constantly talking to Netflix (and other domains, even when using my PC and not interacting with the "smart hub".) I haven't opened the Netflix app in at least two weeks.
The other one all in green (allowed for now), is my Echo Dot with Alexa. That thing is talking to Amazon constantly...