Domain pointing to my Origin - How do I block this?

I have had domains point to my Origin IP it seems by previous owners - my host is useless and I have no idea how they cannt just deny the domain connections to my IP address - my domain is - I am being cloned by - I have set in my .htaccess this:

Options FollowSymLinks

RewriteEngine On
RewriteBase /

RewriteCond %{HTTPS_HOST} !^$
RewriteCond %{HTTP_HOST} !^$ 

This is rewriting the domain back to me on HTTPS and HTTP connections - I have a page rule in Cloudflare performing the 301 redirect. My issue is now I have no clue how to stop as this forwards to my main site and is exposing the origing!

This might slow them down. In my .htaccess, I've done this to block non-Cloudflare connections:
    RewriteEngine On 
    RewriteCond %{HTTP:CF-IPCountry} ^$
    RewriteRule ^ - [F,L]

It just checks for a Cloudflare header, and if it’s missing, rewrite it to nothing. Maybe your approach is just missing the actual RewriteRule that worked for me.