Each Cloud NAT gateway provisioned in GCP incurs hourly charges for each external IP address attached, regardless of whether traffic is flowing through the gateway. In many environments, NAT configurations are created for temporary access (e.g., one-off updates, patching windows, or ephemeral resources) and are never cleaned up. If no traffic is flowing, these NAT gateways remain idle yet continue to generate charges due to reserved IPs and persistent gateway configuration. This is especially common in non-production environments or when legacy configurations are forgotten.