Services hosted on GCP didn't lose any traffic during this incident. This was a control plane outage, not a data plane outage. That means that if you needed to go in and adjust something to resolve your own outage, you were in trouble, but if your services were healthy, nothing bad happened.

As the time of the outage increases, service health probably trends to zero without being able to manage the service... but for a few hours, it's not a disaster. Usually.

The Google Cloud was almost unaffected, during the outage you could not log into the cloud console or use tools like gcloud - but the services itself (vms, gke, pubsub, etc) kept working throughout the outage.