Found that cookies from upstream server (which us under CloudFlare protection) are stripped if their name starts with leading dot, for example .app-id=12345 .
CF doc says that: Cloudflare strips any header that contains dots (.) from origin web server responses. For example, the origin web server header test.header:data is removed by Cloudflare’s proxy., https://support.cloudflare.com/hc/en-us/articles/200170986-How-does-Cloudflare-handle-HTTP-Request-headers-
I am aware the leading dot cookies have been deprecated by RFC 6265 however is there any way to allow them in CloudFlare? I am using Free Plan.