App Service (Windows, .NET 10) returns 503 SiteRoutedToIncorrectWorker on main site AND SCM - persists after restart, stop/start, scale, slot swap,

Our production App Service (Windows, .NET 10, Premium v3 plan, South Africa North) has been returning HTTP 503 SiteRoutedToIncorrectWorker since yesterday evening, with no deployment or config change made at that time.

Symptoms:

• Both the custom domain and the default *.azurewebsites.net hostname return 503 SiteRoutedToIncorrectWorker.
• The SCM/Kudu site for the same app also returns 503 Server Unavailable, so we cannot use Kudu, Log Stream, or even Web Deploy (Web Deploy fails with "Could not connect to the remote computer ... using Web Management Service ... The remote server returned an error: (503) Server Unavailable").
• Resource Health shows an ongoing "Unknown - unable to determine the health of your Web app" event.
• We separately found and fixed a real, unrelated bug (a malformed Key Vault reference with a trailing slash causing an ASP.NET Core startup crash loop, confirmed via 500.30 errors in App Service diagnostics). That is confirmed fixed - no more startup exceptions - but the SiteRoutedToIncorrectWorker 503 persists independently of that fix.

What we've already tried, none of which helped:

• Restarting the App Service
• A full Stop then Start (not just Restart)
• Scaling the App Service Plan instance count up and back down
• Testing the "staging" deployment slot directly - same error
• Creating a brand new App Service in the same subscription/region - also affected

This looks like the front-end routing table is stuck pointing at a worker that no longer serves this site. I found one very similar report (site + SCM both 503, no prior change, restarts not helping) where it needed a Microsoft engineer to intervene directly: https://learn.microsoft.com/en-us/answers/questions/1030991/azure-app-service-site-and-scm-site-return-503-una

Has anyone resolved this without going through a support ticket, or can a Microsoft engineer help investigate the backend worker/routing assignment for this app? This is a production system that has now been down for a full day.