Nginx not directing to gunicorn socket, returns 404 Not Found

I found the cause, the related ssl certificate for this domain was a part of another certificate on the same server, it should not cause a big trouble if configured correctly I think.

This warning made me think about it:

nginx: [warn] conflicting server name "example.com" on 0.0.0.0:443, ignored

I checked all these to see what's going on:

sudo less /var/log/nginx/error.log: the Nginx error logs.
sudo less /var/log/nginx/access.log: the Nginx access logs.
sudo journalctl -u nginx: the Nginx process logs.
sudo journalctl -u example.com: Flask app’s Gunicorn logs.

But the solution I did was that I removed it from the other domain using this command by updating the certificate, I removed mine from the list:

sudo certbot --cert-name xxxx.org -d xxxxx.com -d yyyy.org -d yyyy.com

then re-created it for this domain.

sudo certbot --nginx -d example.com -d example.co -d www.example.com

And the final nginx config was this:

server {
    server_name example.com www.example.com example.co;
    access_log     /var/log/nginx/domains/main.example.com.log;
    error_log  /var/log/nginx/domains/main.example.com.error.log error;

    location / {
        include proxy_params;
        proxy_pass http://unix:/var/www/example.com/azom_care.sock;
    }

    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot

}
server {
    if ($host = www.example.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


    if ($host = example.co) {
        return 301 https://$host$request_uri;                                                                                                                                                                          } # managed by Certbot                                                                                                                                                                                                                                                                                                                                                                                                            
    if ($host = example.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


    listen 80;
    server_name example.com www.example.com example.co;
    return 404; # managed by Certbot

}

and the it worked correctly Alhamdullellah!