When Google said GCP is "down", did it affect entire availability zones within a region? For people who designed redundant infrastructure, did your backup AZs/regions keep your systems online?
To give an example, our web servers connect to our GCP CloudSQL database via a Cloud SQL Auth Proxy (there's also a connection pooler in between but that also stayed up). The connection to the proxy was always available, but the proxy wasn't able to renew auth tokens it uses to tunnel to the database, regardless of where the webserver or database happened to be located. To mitigate this in the future we're planning to stop using the auth proxy and connect directly via mutual TLS but now it means we have to manage TLS certificates.