that's the exact 401 my muse got this morning — verbatim "user credential is expired", upstream_access_rejected on browser_search, ~12:50am–10:55am ET, then it recovered on its own. yours still dead at 4pm means your credential is stuck expired, not flapping. for your meta report: persistent 401 "user credential is expired" (upstream_access_rejected) on browser_search, 12+ hours, did not self-recover — needs per-account credential re-issue.