An unknown domain serving contents of my sites

Timothy Lee asked:

I found that an unknown domain like www.aaa.com serving exactly the same contents (html, js ,css, any asset) of my site: myname.me.

And the API as well, for example, www.aaa.com/api/user get the same response as myname.me/api/user.

How can I block this domain from serving my thing?

How does it make this, redirect directly to my domain? Proxy? DNS?

I use VPS and I use nginx, here my nginx config,
This is the redirection to https:

server {
    if ($host = example.me) {
        return 301 https://$host$request_uri;
    }

    listen 80 default_server;
    listen [::]:80 default_server;

    server_name example.me;
    return 404;
}

This is the proxy from https request to my application running on port 3000:

server {
    root /var/www/html/example
    server_tokens off;

    index index.html index.htm index.nginx-debian.html;

    server_name example.me;
    # add_header Cache-Control no-cache;

    location / {
        # First attempt to serve request as file, then as directory, then fall back to displaying a 404.
        # try_files $uri $uri/ =404;
        proxy_pass http://198.51.100.1:3000$request_uri;
    }
}