When casting from the youtube app using chromecast, users are no longer able to sign-in to access their premium features. The error message simply says that you can't sign in but can continue to use the product as a guest. This means that people who pay for premium have to watch ads.
There was a post from YT that this was done intentionally as a way to phase out old chromecast devices. Is this true?
This started happening to me a couple days ago. I haven't been able to sign in to YouTube since then, but I can still cast YouTube videos from my phone. The Chromecast I have is the 4K version they supplied with the Stadia bundle. Fingers crossed they fix it soon. No idea whether content creators are getting a slice of my premium subscription while I'm not signed in.
Refering to this tweet.
So settings randomly reset to default, so autoplay sometimes cannot be disabled from your mobile device & if your a Premium YouTube member ads can randomly appear, all the time if your using the Youtube App remote, the latter useless to access your subscriptions.
Oh by the way, you cannot even buy a Chromecast with Google TV from Google's own store website in New Zealand - they are still selling the now non-functioning Chromecast (3rd generation) which doesn't even support the resolution of the Chromecast Ultra.