Basically, the only way is to disconnect the TV and use it as a dumb screen. Lineageos supports a few set top boxes (see here).
I heard (take it as hearsay) that some smart TV periodically capture screenshots of what’s on screen and upload it, so it actually disconnecting the tv from the network could (again, hearsay) make a real difference.
Why do people think we care why they decided this or that? (same goes for people who switch to linux, or upgrade their gear, or whatever)