How to proxy get parameters in nginx?

Question

Nginx

I have the following nginx configuration (simplified):

# Frontend
server {
        listen *:443 ssl http2;
        server_name example.com;
                proxy_set_header          Host             $host;
                proxy_set_header          X-Real-IP        $remote_addr;
                proxy_set_header          X-Forwarded-For  $proxy_add_x_forwarded_for;
                proxy_set_header          X-Forwarded-Host $server_name;
                proxy_redirect               off;
                proxy_read_timeout        60s;

        root /var/www/front;
        location /api {
                proxy_pass      http://127.0.0.1:8888;
       }
        location / {
                if (!-e $request_filename{
                        rewrite ^(.*)$ /index.html;
                }
                index  index.html;
        }
}

# Backend
server {
        listen 127.0.0.1:8888;
        root /var/www/api;
        location / {
                index  index.php;
                try_files $uri $uri/ /index.php?$args;

        location ~ \.php$ {
                fastcgi_pass backend:9000;
                fastcgi_index index.php;
                fastcgi_cache fcgi;
                fastcgi_cache_valid 200 30m;
                include fastcgi_params;
                try_files $uri =404;
                fastcgi_split_path_info ^(.+\.php)(/.+)$;
       }
 }

all POST requests coming to https://example.com/api/... are proxied
to the backend and further processed by fastcgi
?key1=value1&ke...
proxied to the backend without losing GET parameters?

Answer 1

With proxy_pass, they are already proxied without loss as they are. And the problem is clearly elsewhere. Apparently the real config should be simplified to a really simple one.
In the project itself, API is being proxyed to a server in the internal network. Everything works great. There is even a change in the original url.