I have no experience with Google support, let alone GCP support. But what I've heard both from inside and from customers, is that unless someone happen to want to help you with your specific problem, it can be a bit of hit or miss situation to get help. Maybe it's different with now GCP, but until I hear first hand experience telling me otherwise, I'm not even considering moving our cloud business to GCP.

We're running production systems making a significant amount of of our revenue, and when, not if, shit hits the fan we need someone with intimate knowledge of the internals to give us undivided attention until it's resolved.

Sometimes it's because we fucked up, sometimes it's the perfect storm of internals working unexpected - all of the time our systems are not working and our customers depend on them for their daily work.