X_ERROR_STATUS_BACKLOG_STALE
Means
a pin in the status-table ratchet has been resolved and left behind
Typical cause
scripts/error-map-backlog.ts still lists a code that packages/http/src/error-map.ts now maps, or one no package declares any more. "Can this code reach a request?" is not derivable from the source, so the classification is pinned and ratcheted — and a pin nobody removes is a pin nobody reads
Fix
the fix names the code and its group — delete that entry from scripts/error-map-backlog.ts