You can block HTTPS to known DoH providers. You can set up an alias in a firewall to load the list from https://public-dns.info/nameservers-all.txt https://publ

You can block HTTPS to known DoH providers. You can set up an alias in a firewall to load the list from https://public-dns.info/nameservers-all.txt https://public-dns.info/nameservers-all.txt. Its a bit of a cat-and-mouse game as it relies on that list being updated frequently and reliably, but its the best you're gonna get for blocking DoH. Also make sure to block outgoing TCP and UDP 853 – this blocks DoT and DoQ too.