Hi, we've been noticing this issue for the past few weeks: when a TV is turned on, unrelated rooms that are also not grouped with the TV may begin playing music.
Here is a Diagnostic captured a minute or two after the issue occured: 605248757
We have 3 tvs in the house, each has either a Beam or an Arc.
To reproduce this occasional problem:
1. Make sure all Sonos products are not playing any audio.
2. Turn on a TV that is connected to either a Beam or an Arc.
3. Observe the connected product will properly begin playing TV audio, but other products will begin playing music.
Let me know if you need any more info, thanks!