We're aware of a problem with Remote Config related to 503 errors. We are currently investigating the problem.
Firebase Status Dashboard
This page provides status information on the services that are part of Firebase. Check back here to view the current status of the services listed below. If you are experiencing an issue not listed here, please contact Support. Learn more about what's posted on the dashboard in this FAQ. For additional information on these services, please visit https://firebase.google.com/.