Sadly the Roku app draining phone battery situation persists on current Roku streaming players also 😞 , it is sadly being returned for a refund now!
But there is hope!
For anyone reading and in the same situation as me there is a an alternative, would you believe private listening can be achieved on XBOX (series S in my case) and by either plugging in your headphone's into the controller or via the MS wireless headphones, its not as slick as the Roku as you have to use the controller for in-app controls, but having watched a TV show last night I am very happy, so this is a good alternative imho and I can see myself switching to it if Roku doesnt fix this issue 😉
Thanks,