Traefik (edge router) intermittently stops adding the 'Access-Control-Allow-Origin' header for several selected endpoints without any apparent reason, requiring a service restart. Unfortunately, this issue has persisted for some time and persists across version changes. The problem has been addressed by adding this header at the Cloudflare level to prevent its recurrence.

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https://community.traefik.io/t/traefik-not-setting-access-control-allow-origin-header/14961