Nginx remove Secure Flag to Cookies from proxied server
I know this is quite old question, but there is no answer here and I couldn't find fine solution for the same problem.
So I forked nginx_cookie_flag_module module and changed it to nginx_unsecure_cookie_module:https://github.com/yumauri/nginx_unsecure_cookie_module
I'm frontend developer, my C/C++ knowledges are super low, but looks like it is working in my tests :) So I reckon it is good enough for development reasons.