Block URL with Nginx

Question

I have a frontend application serving at port 8080. There is backend application online office, serving at port 9980.

Now, I want to block download of files. So, application doesn't provide this feature out of the box. We decided to go with nginx to block the download.

http://BACKEND:9980/cool/http://FRONTEND/index.php/apps/richdocuments/wopi/files/148_oc77y9fz750l/download/9V2pPSf82J8QtaHccNXOKeIQDbHTWGRSOMGPPiuw4P8gDyo9SbpszHk5I7tpH9CY?WOPISrc=http://BACKEND/index.php/apps/richdocuments/wopi/files/148_oc77y9fz750l&compat=/ws

Flow is nginx in front listening at port 80 -> proxies the request to frontend at port 8080 -> When user clicks on download it get serves at port 9980

Is there a way I can block the download when I get /download in the URL.

Below is for front end

server {
    listen 80;
    listen [::]:80;

    server_name _;

    client_max_body_size 0;
    underscores_in_headers on;

    location ~ {
        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-Proto $scheme;
        add_header Front-End-Https on;
        proxy_headers_hash_max_size 512;
        proxy_headers_hash_bucket_size 64;
        proxy_buffering off;
        proxy_redirect off;
        proxy_max_temp_file_size 0;
        proxy_pass http://127.0.0.1:8080;
        
    }
   
   location = /.well-known/carddav {
    return 301 $scheme://$host/remote.php/dav;
   }  

   location = /.well-known/caldav {
   return 301 $scheme://$host/remote.php/dav;
   }

Below are all different location block I tried for backend but return no success.

   location ^~ /download {
      proxy_pass http://127.0.0.1:9980;
      proxy_set_header Host $http_host;
       deny all;
       return 403;
   } 

  location ~* /.*download.* {
        deny all;
        return 403;
  }

   location ~* /.*download.* {
       internal;
        proxy_pass http://127.0.0.1:9980;
        deny all;
        return 403;
    }


  location ^~ /download {
   deny all;
   return 403 'blocked';
  }

 location ~ ^/(c|l)ool {
   proxy_pass http://127.0.0.1:9980;
   proxy_set_header Host $http_host;
  deny all;
 return 403;
 }