May I ask what’s your Browser Cache TTL setting? Is it set to the Respect Existing Headers? If yes, then the HTTP cache headers are coming from your origin host/server or the framework you’re using is producing them
Any Nginx modules running which would interfere or produce the result?
x-page-speed: ngx_pagespeed
x-cache: MISS
May I ask if those HTTP cache headers defined in the main nginx.conf file or rather in the .vhost file for the domain?
Otherwise, may I ask have you used some Rules at the Cloudflare dashboard? Either Cache Rules or Transform Rules with Modifying Response Header?