It's simple. Just don't give your Smart TV your wi-fi password. Ever. The Smart functions are terrible implementations anyway. Plug in something you trust more, like a Plex box, an Amazon Fire Stick or a Chromestick and let your TV be a dumb device that just displays whatever video signal you feed it.
Samsung Smart TVs got caught *browsing your network shared folders and sending your filenames to a server in South Korea*. There is no possible legitimate excuse for that. Don't trust consumer electronics devices!
Personally, I'd never trust an Alexa or similar device either, but YMMV.