Trying to do something with uploadable.name works on localhost, but not under reverse proxy

[TissuePowder]

For file uploads, I am trying to get the original filename of the image/video and set it as source for a post.
The client/html/post_upload_row.tpl file has the following line to show the filename on a node:

<span class='filename'><%= ctx.uploadable.name %></span>

So, supposedly uploadable.name should be usable elsewhere in the code too.
Now I am trying to edit the file client/js/controllers/post_upload_controller.js with the following:

if (uploadable.url) {
    post.source = uploadable.url;
} else {
    post.source = uploadable.name;
}

This works fine as expected when I am using the site through localhost, at ip 127.0.0.1 (directly or through ssh -L), but fails when I deploy the site behind a reverse proxy and try to access it through https://example.com. Fails as in the source gets null value.

I don't understand what's happening. I guess it's a faulty js code that my browser doesn't care when executing on localhost, but stops it from happening when it's on a public site with tls? If anyone can shed some light, I will be grateful.

[TissuePowder]

This is my full nginx config file, only redacted my deploy domain name, except that everything is here. Did I forget to x-forward something?

limit_req_zone $binary_remote_addr zone=throttle:10m rate=25r/s;

server {

  server_name example.com www.example.com;

  access_log /var/log/nginx/reverse-access-example.com.log;
  error_log /var/log/nginx/reverse-error-example.com.log;

  location = /robots.txt {

    return 200 "User-agent: *\nDisallow: /\n";
  }

  client_max_body_size 10000M;
  client_body_timeout 30s;
  server_tokens off;


  location / {

    #    auth_basic "Restricted Content";
    #    auth_basic_user_file /etc/nginx/.htpasswd;

    limit_req zone=throttle burst=5 delay=3;


    proxy_pass http://127.0.0.1:8080/;

    proxy_http_version 1.1;
    proxy_cache_bypass $http_upgrade;
    proxy_set_header Connection "upgrade";
    proxy_set_header Upgrade $http_upgrade;

    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-Scheme $scheme;
    proxy_set_header X-Forwarded-Proto $scheme;
    proxy_set_header X-Forwarded-Host $host;
    proxy_set_header X-Forwarded-Port $server_port;
    proxy_read_timeout 1d;
    proxy_set_header X-Script-Name /szuru;
    error_page 500 501 502 504 505 506 507 508 509 510 511 @err;
    error_page 503 @throttle;

    add_header Strict-Transport-Security "max-age=63072000; includeSubDomains" always;
    add_header X-XSS-Protection "1; mode=block";
    add_header X-Frame-Options "SAMEORIGIN";
    add_header X-Content-Type-Options "nosniff";
    add_header Referrer-Policy "strict-origin";

  }

  location @err {

    return 500 "server error. please try again later.";
    default_type text/plain;
  }

  location @throttle {

    return 503 "we've detected abuse on your ip. please wait and try again later.";
    default_type text/plain;
  }

  listen [::]:443 ssl http2;
  listen 443 ssl http2;
  ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
  ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;
  ssl_trusted_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
  include /etc/letsencrypt/options-ssl-nginx.conf;
#  ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;
  ssl_stapling on;
  ssl_stapling_verify on;

}


server {

  if ($host = www.example.com) {

    return 301 https://$host$request_uri;
  }

  if ($host = example.com) {

    return 301 https://$host$request_uri;
  }

  listen 80;
  listen [::]:80;

  server_name example.com www.example.com;
  return 404;
}

[TissuePowder]

Uh it was a cloudflare caching problem. Turning off the caching in CF dashboard and/or using something like app.min.js?v=2 in index html fixes this.