Franzfume there's no night mode. Is true ?
Technically, that WAS true when what you read was written. GrapheneOS camera depends on some upstream (Google) modules (CameraX) to implement advanced features, and they've been sluggish bringing these special features into CameraX.
I actually use both GrapheneOS camera as well as GCam. I prefer GrapheneOS camera, but occasionally benefit from some feature that doesn't work in it. Just disable network in GCam and it should be pretty safe from spying. Note that you do NOT need to install gservices for gcam to work. For me, that would be a deal breaker.