Your router is using regular DNS over port 53. If your browser is using DNSoverHTTPS it will use port 443 and encrypted. It is literally flying through the firewall unless you specifically have it set to use regular DNS. I would test tbh. Are you sure your browser is always using your router DNS? Google Chrome is notoriously known to jump straight to Google and even ping root DNS servers. If all of your requests are being resolved by your DNS on your router, good. I think using the DNS in your router is more secure than using a 3rd party DNS any day and it's much much faster. But all operating systems appear to slowly move to DNS over HTTPS so you will most likely have to revisit that question and double check if it's not bypassing your DNS.