Vercel CDN Stops Caching Vary: Cookie Responses

Vercel CDN no longer stores origin responses whose Vary header includes Cookie, because cookie-specific values create many rarely reused cache entries. Affected responses still serve normally but return x-vercel-cache MISS, with Runtime Logs showing vary_key_denied:cookie. Developers should drop Cookie from Vary when responses are identical, or add Cache-Control: private when they depend on cookies. Other Vary headers are unchanged.