Firefox checks if use-application-dns.net is blocked, if it finds that it isn't blocked it ends up trying to use DoH. https://support.mozilla.org/en-US/kb/cana

Firefox checks if use-application-dns.net is blocked, if it finds that it isn't blocked it ends up trying to use DoH. https://support.mozilla.org/en-US/kb/canary-domain-use-application-dnsnet https://support.mozilla.org/en-US/kb/canary-domain-use-appli...