Check if you received a notification recently stating "Camera remove
from your account". That is what I received, however the device was
still working without camera features. Not sure if that was by design or
bad firmware/softwre push that broke it.
I don't think you are alone here. This morning I received a notification
"camera removed from your account". The camera in question was the
Google Hub Max. I use to be able to turn it on and off, use it as
another camera as I have a nest aware plan. ...