Totally unrelated to Channels (other than the fact that we mainly use Channels lol), but we just ran into an issue and trying to see if anyone has encountered it.
Our Siri Remote (most recent Apple TV 4K) has suddenly started to turn off our TV, even when the Apple TV isn’t even connected or plugged in! We can just pickup/move/shake the remote and it happens.
Anyone else seen this?
Did you program the Apple TV remote to control your tv or any devices? It can be programmed to control devices via IR. If the Actual Apple TV is disconnected from your TV both power and HDMI, then CEC would not work, so, that is why i suspect IR control.
However, the current generation (and past) Apple TV Siri Remote does not have a gyroscope or an accelerometer, so just picking it up/shaking it would not do anything in of it self.
If you have touch enabled, then you may be touching the touch sensitive area of it and that is triggering a IR command. Or maybe pressing the side Siri button.
Another thought, have u looked for other culprits, like the actual TV remote that may have fallen into the dark abyss of between a couch cushion, or something like that? 
That’s just it, I don’t recall doing any kind of programming of the remote to send IR signals. For now I switched to the Channels app on the built-in Android TV until I have a chance to investigate further (too many other irons in the fire right now).
Maybe I just need to try and reset the remote and see if that clears it.
It does it automatically at setup. If it can’t control power and volume with cec compatibility it will use data gathered in the cec/hdmi handshake to program itself with ir. At least it did with my lg oled cx series. You can verify what it’s using in the Apple TV settings under remote section. I’ve noticed weird issues when the battery on the remote gets low but that’s mostly volume issues solved with a remote reboot.