Your new smart TV is so cheap because it's collecting and selling your data
businessinsider.com
businessinsider.com
Consumer reports has a write up to let you know what to disable based on the manufacter.[1] I’m still tempted to do wireshark.
[1]https://www.consumerreports.org/privacy/how-to-turn-off-smar...
Or the manufacturer cuts a deal with your broadband provider and gets a backdoor out via your WiFi hub, if you use the standard one they gave you. Or a hidden app on an Android phone that the Android TV chats to when it’s nearby.
IP over HDMI is also a thing.
I am never connecting our Sony smart TV directly to the Internet, like you we have an AppleTV but it’s only a matter of time before you won’t be able to buy an unconnected TV at all.
If you have a lot of devices to plug in a mixer may also be needed.
Or would it be constantly scanning and looking for an open access point, and get online once a neighbor leaves his open for a few minutes?
Aside from stupidity like that, having wifi on might be susceptible to vulnerabilities in the network stack or otherwise pollute the local airspace.