Some smart TVs also run content recognition algorithms on whatever input you give them, and upload it to the company servers who analyze it for profiling your interests. Maybe even sell that information for profit.

Link for more info: https://www.zdnet.com/home-and-office/home-entertainment/you-should-turn-off-acr-on-your-tv-right-now-and-why-it-makes-such-a-big-difference/