Most “smart” TVs (which can & do fetch currently-airing show data from each channel’s metadata streams, when tuned to that channel) rely on internet connectivity to show the channel guide, so implicitly, that they act slow & buggy when used without internet.

Some “smart” TV’s tuner apps, seem to get buggier & less convenient after updates, as if the manufacturer decided to gimp the tuner, in an effort to force more streaming usage.