This can be seen on the following dashboard.
https://grafana-labs.wikimedia.org/dashboard/db/revisionsliderenablesdisables
While logged in to the admin site everything works just fine.
While calling the anon site 2 calls to the production grafana fail and return 403s while trying to load the grafana proxy.
The calls are to:
https://grafana-labs.wikimedia.org/api/datasources/proxy/3/render
And get the response:
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"> <html><head> <title>403 Forbidden</title> </head><body> <h1>Forbidden</h1> <p>You don't have permission to access /api/datasources/proxy/3/render on this server.<br /> </p> </body></html>