Even if it does have phone-home functions, why does the camera itself need internet access?

IMO, audit the hardware for wireless radios (PoE cameras shouldn't have them), and put them on a camera-only VLAN that can only talk to the video server.

Maybe not suitable for super secure TS locations, but in general should be fine for 99% of situations.

I think if you've got total control over them, not a problem compartmentalising. Problem is, they're like loitering munitions, next person comes along and connectes them up to a router or misconfigures a firewall... Much as I hate e-waste sadly best place is in the bin. They're cheap but, easy come easy go.