Your company just experienced a Google Kubernetes Engine (GKE) API outage due to a zone...

https://cloud.google.com/kubernetes-engine/docs/concepts/types-of-clusters#regional_clusters

A regional cluster has multiple replicas of the control plane, running in multiple zones within a given region. Nodes in a regional cluster can run in multiple zones or a single zone depending on the configured node locations. By default, GKE replicates each node pool across three zones of the control plane's region. When you create a cluster or when you add a new node pool, you can change the default configuration by specifying the zone(s) in which the cluster's nodes run. All zones must be within the same region as the control plane.