The OS is still unstable

sounds like you have a crappy TV then. I literally never have to touch my LG.

tries to apply a bunch of filters that need to be disabled

well sure, but image processing in general is good to have in a TV. I wouldn’t say having options on how to do that is a bad thing.

has extreme lag unless gaming mode is being used

again, that’s due to the image processing. lag is fine if you are just watching the TV, and if you want to play games there is gaming mode. so i’m not sure what your complaint even is here.

and has stupid UI decisions like putting the audio level exactly where the subtitles usually are so that changing audio will obfuscate them.

this has nothing to do with the “smart” functions.

Once every 24h I‘m also getting a warning that the tv is not connected to the internet, despite network connectivity being explicitly disabled.

again, this is not a thing for most smart TVs, you just have a shitty one.