The data plane sits where the packets are
Classification, inspection and enforcement happen in a fast path attached directly to the interfaces. There is no hairpin to a proxy host and no second appliance in the path. The firewall that routes the packet is the firewall that decides on it.
The control plane owns the decision
One pipeline produces one verdict per session. Identity, application, category, reputation and content findings are gathered before anything is decided, so two subsystems can never disagree about the same flow.
The management plane is yours
The console is a container you run on your own server, under your own domain. It holds the tenancy tree, the policy sets and the counters. Nothing about the organisations you manage is stored anywhere else.
Failure is a designed state
If the console is unreachable the firewall keeps enforcing the policy it already has. If the engine stops, the platform own filtering continues. Neither component is a single point of failure for the other.