The GN video explained it pretty well.I recommend watching it if you have a spare couple hours and can stand some of the worst marketing speak I've ever seen.

IDK what phones do these days, but the LG units have multiple microphone systems. Some of them are active even when apparently disabled via switch or UI. At least one is confirmed to constantly listen for the wake word.

I can imagine that you can do the voice recognition for "Hi LG" locally without sending anything to the internet, and then start sending when the command is recognized. I don't know anything about this polemic and I obviously lean to "tech giant is spying on you" given the history of tech giants, just speculating.

The video by gamersnexus showed that it is actively listening even when completely unplugged from network and stores voice capture from the environment + actively sends data on whats on the screen back to LG. hope you dont use an LG monitor to look at your medical records!