As of Pi-Hole release 4.4 it will automatically disable DoH for all Firefox browsers it serves by sinkholing the canary domain [0]. For Chrome it appears that

As of Pi-Hole release 4.4 it will automatically disable DoH for all Firefox browsers it serves by sinkholing the canary domain [0]. For Chrome it appears that they are just upgrading to DoH for the existing DNS servers if it is possible. Since a local Pi-Hole server wouldn't be in their possible upgrade list it would be left untouched. [0] https://support.mozilla.org/en-US/kb/canary-domain-use-application-dnsnet https://support.mozilla.org/en-US/kb/canary-domain-use-appli...