If I understand it correctly, you're not really casting to the phone, the oculus app is mirroring what's on the Quest, which I believe is something different. The only casting is from the phone.
I hope they update the app as currently I can't cast to my Android TVs from either the iphone app of from the Android version on my tablet. I can mirror from the tablet to the TV though as they're both Sony.
Edit: I'm not an expert but perhaps it's done via the phone/tablet app instead of directly from the Quest because the intention is to have the ability to cast everything the Quest is displaying, whereas if it's done directly from the Quest, it would rely on each app having the cast function built-in which developers don't always bother with. Like I say though I'm no expert.
No the app needs an update.
It doesn't seem to cast to devices with Chromecast built in and some people are reporting it not casting to other devices also.
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