Gmail API users.history.list: appropriate support route and minimum diagnostic evidence

Which documented developer-support channel is appropriate for seeking guidance about repeated rate-limit reports from users.history.list for a personal gmail.com mailbox?

The application’s earlier records retained a normalized rate_limited result, but not enough per-attempt HTTP status and structured Google error information to identify the enforcement category. Available project-level quota observations do not establish per-user usage or restriction clearance. We are not claiming a confirmed Google defect, quota exhaustion, or entitlement to private technical support.

What minimum non-sensitive response metadata should be captured during a separately authorised observation, and which channel can advise on escalation if a persistent restriction is confirmed? The Gmail API support page points to this developer community and also describes a specialist route for Google Workspace administrators; applicability of that private route to this case has not been established.

This is a question about routing and evidence prerequisites, not a quota-change request. No credentials, project or account identifiers, request/response dumps, or mailbox content are included.