Graph http 449 throttled

Would suggest locating the issues first:

•    Correlation headers: Capture client-request-id, request-id, and x-ms-ags-diagnostic in every failed call. 
•    Retry hints: Log Retry-After and any throttling headers. Respect the longest hint across chained calls.
•    Request identity: Record whether calls are delegated (user) or application (SPN), plus appId, tenant, and scopes.
•    Endpoint signature: Log the full URI (minus PII), especially the resource and query options ($select, $filter, $top, etc.).
•    Concurrency context: Track queue depth, parallel workers, and per-endpoint in-flight counts.
Dashboards to build (App Insights or equivalent)
•    Errors by appId: 429/449 counts grouped by application, credential type (delegated vs app), and environment slot.
•    Errors by endpoint: Identify hot endpoints (e.g., /users, /messages, /drive/root/children, /sites/{id}/lists/...).
•    Temporal patterns: Heatmap of throttles by minute/hour; correlate with scheduled jobs and vendor integrations.
•    Burst detection: Distribution of request rates and concurrent calls per app; flag spikes above your soft caps.
This quickly tells you if a single app or a specific workload (often SharePoint, Mail, or Directory) is the problem.