I use my phone to start HBO Max and then use the Chromecast built-into my Vizio TV to watch it there. When I do this, I can see the Arc’s light blinking, quickly increasing the volume to max for absolutely no reason. I have to immediately open the Sonos app and reduce the volume slider or my neighbors will hear it down the street. When I use Airplay instead of Cast (even though Cast also used the HBO Max app built into my tv), this issue doesn't occur.
Why is this happening? I have an Arc with two bonded era 300s.