Hello Leftblank15,
Depending on how your network is configured, this is general practice.
Your Modem/Router receives its public IP address from your ISP, it also receives your ISP’s DNS servers, these settings are saved on your Modem / Router.
While you are using your router’s IP address as your DNS server it is actually forwarding the request to the DNS servers that were discovered from your ISP.
If you log into your router you can update the DNS IP that it is handing out to all of your network devices to something like 8.8.8.8. or 8.8.4.4 (Google DNS) or (IBM) 9.9.9.9 or (Cloudflare) 1.1.1.1 or 1.1.1.2 in the local network DHCP settings instead of using the router’s IP address.