I was using it yesterday in the mobile app. Unless they just slapped the new UI on an older model.
It’s no longer there, I think?
I think they (partially?) rolled it back. I tried out the voice input yesterday, but it’s missing from the app today.
They just released the text chat model which still uses the same old audio interface as 4. The new audio/video chat stuff is not out yet (unless you are a very lucky early beta user).