if you have third party airplay speakers, and set up a scene in homekit to play music to them. One of your homekit hubs will wake up to send music to those speakers. For a HomePod this isn't really noticable, But for some reason the aTV feels it needs to fully wake itself and the TV up to do it. But you have no choice over which device will take over.
so "Candlelit Dinner" scene, 2 devices in the scene, the dining room light set to a dim level, and the sonos speaker playing a jazz playlist from Apple Music.
When you run the scene, there's a good chance the TV in the other room will turn itself on when you do.