FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
Article Id 191845
This article provides an explanation of policy-4294967295 under FortiView.

A policy with the name 4294967295 may be seen under FortiView > Policies.

Policy-4294967295 refers to a local in policy.  Local in policies are the policies where the traffic terminates on the FortiGate itself whereas firewall policies refer to traffic destined to networks behind the FortiGate.

On v5.4, the local policy ID has changed from policy 0 to policy 4294967295 for the incoming request. Any traffic terminating at the FortiGate will be handled by new policy ID.  The policy 0 ID is still there but only shown when traffic is initiated by the FortiGate such as DNS requests.

The default local in policy does not appear in configuration.