Anyone who owns an LG smart TV must inform all guests and family members that they are being monitored – this is required by LG’s current terms of use. Meanwhile, LG monitors install potential malware and surveillance software on a connected Windows computer.
I’m probably an unsuitable person to ask this since my TV is basically a glorified monitor, but from what I could tell there are no downsides except for the obvious one being that I can’t update my TV. But considering much bloat and spying is going on with (LG) smart TVs, I don’t mind it all.
I use Twitch, YouTube, and Jellyfin on mine, and it’s been awesome. I hadn’t used any other functionality or apps the TV comes with before rooting and I likely won’t in the future. So even if some of them didn’t work, I couldn’t care less.
Maybe do some research and find out for your specific model?