For those of us unfamiliar with GCP, do you mean that the default-route of your VM was unable to route its traffic?
Or is there a routing config running on customer VMs that GCP live-manages?
GCP has a virtual networking stack to support a bunch of crazy (and awesome) features Google has built. Unfortunately the complexity here seems to hurt power-users like us. In this case it appears that for some unknown reason the node failed to program its network stack when coming up, meaning it was completely unavailable (even the metadata service used internally by google failed).