Receive 404 Not Found for a Flask app when I use Nginx as reverse proxy with Gunicorn socket

Question

I am getting this error only on some routes and not all,rest everything is working fine below is the code, i have used nginx as a reverse proxy with gunicorn and wsgi, dont know why getting this error only on some new routes

    server {
        listen 80;
        listen [::]:80 default_server;
        listen 443 ssl;
        root /home/ubuntu/selexmb/sassmlapp/frontend/build;
        server_name abc.com;
        ssl_certificate /etc/nginx/certificate/nginx-certificate.crt;
        ssl_certificate_key /etc/nginx/certificate/nginx.key;
    
        location / {
                    try_files $uri /index.html;
            }
    }
    
    server {
        listen 80 ;
        listen [::]:80 ;
        listen 443 ssl;
        server_name api.abc.com;
        ssl_certificate /etc/nginx/certificate/nginx-certificate.crt;
        ssl_certificate_key /etc/nginx/certificate/nginx.key;
    
location / {
      include proxy_params;
      proxy_pass http://unix:/home/ubuntu/selexmb/sassmlapp/backend/app.sock;
    }
}