I’m using a Roku sound bar on a really old tv that doesn’t have arc, it only has an optical audio cable. So I have to use both an hdmi cable and the optical cable to get sound in my sound bar.
When I set the sleep timer on my old Visio tv and it expires, the tv turns off but the Roku in the sound bar continues to play the audio of whatever is streaming. This is very annoying and has never worked I’ve even put my tv and Roku power into a Alexa powered switch. That voice action with a voice timer turns off both but when the switch becomes enabled, the sound bar and tv turn on again but not consistently enough to teach my wife to use voice controls for this tv.
on my other tvs I use Roku sticks but these are newer and have arc hdmi ports so when these sleep timers expire, their non-Roku sound bars turn off.
I think that this is either a situation where the Roku sound bar doesn’t sense that the tv sleep timer has turned off the tv or the sound bar Roku need to be updated to use a sleep timer that turns off both the tv and the sound bar. (note that the sound bar remote does power tv on and off)