You should have seen the extent to which the rest of the team and I tried to resolve customer issues.
Random App Engine app getting 500s calling an Open ID endpoint (the service wasn't strictly speaking managed by GCP). I absolutely could not reproduce this and had no other reports, but I knew it was happening for the customer. I examined everything that could be different... After 2 weeks I finally got it: The customer app was running in a different data center compared to where I was testing. Calls to the API endpoint were timing out internally (pretty aggressive timeout interval). It turns out the Open ID service wasn't running in the same data center region. That should not have been the case but occurred because the internal BigTable service had to be upgraded in a particular region and hence all App Engine apps in that region were moved to another one - a fairly seamless process. The Open ID service unfortunately wasn't provisioned in that region (it's not a dependency of App Engine). Once I identified the issue it was a matter of telling the on call SRE about it who then spun up Open ID in that region and thereby resolved the issues in a matter of 5 minutes.
Often a new support case meant discovering platform limitations - for example running into BigTable anti patterns because App Engine Datastore allocated IDs sequentially by default. That could cause poor read / write performance, in part due to automatic sharding behavior of BigTable. We later switched to snowflake IDs.
And then there were lots of Java folks used to Classpath scanning (default behavior of Spring Framework?) which for larger projects caused App Engine container startup to exceed the allowed time limit. That became a user education issue for which we then had to write an in depth article.
Good times :)
I absolutely hated dealing with billing inquiries though... so difficult to map someone's code to billable operations. Some SDK methods were of course utilizing multiple billable operations. Determining SLA violation refunds was much easier.