Dockerised shiny app greyed out after few min of inactivity

I maintain a Dockerised shiny R hosted in Ubuntu with Ngnix web-server running in port 5050. It works fine, however greyed out after inactivity for some time.

To circumvent this I modified the proxy_read_timeout parameter default file in /etc/nginx/sites-available as below

location /XXX/YYY/ {
      rewrite ^/XXX/YYY/(.*)$ /$1 break;
      proxy_pass http://localhost:5050;
      proxy_redirect http://localhost:5050/ $scheme://$host/XXX/YYY/;
      proxy_http_version 1.1;
      proxy_set_header Upgrade $http_upgrade;
      proxy_set_header   Connection "upgrade";      
      proxy_read_timeout 20d;
      proxy_buffering off;
    }

I also increased numbers in all below files

/proc/sys/net/ipv4/tcp_keepalive_time
/proc/sys/net/ipv4/tcp_keepalive_intvl
/proc/sys/net/ipv4/tcp_keepalive_probes
/proc/sys/net/ipv4/tcp_retries2

Additionally, I added below lines /etc/nginx/nginx.conf

http {
     fastcgi_read_timeout 1d;
     proxy_read_timeout 1d;
}

Furthermore, I added below lines of code in server.R

output$clock = renderText({
                invalidateLater(5000)
                Sys.time()
            })  

But unfortunately, nothing solved my problem. However I noticed that when I use ip-address:5050 to run my app I don't see greyed out, but when I use ip-address/XXX/YYY then it happens.

I am using Cloudflare free subscription - dose it have any impact on above issue? If this is the case then what is the solution?