As soon as the idiocy known as DNS over HTTPS (DoH) first appeared, I was one of the first to warn how this was a fundamentally bad idea. It breaks the widely used DNS-based controls that individuals, families, and businesses have deployed in recent years to restrict access to malicious and unwanted (porn, social media, etc) domains by allowing a user with a DoH enabled browser to bypass these security measures entirely.
As a result, I was also one of the first to develop a blocklist that could be used by DNS blocklist enabled firewalls such as pfSense, to block user attempts to access DoH servers, and thus bypass network controls. As I said at the time, my list was a temporary measure until a more sustainable solution was available.
With the introduction of a specific DoH server feed in the latest version of the pfBlockerNG plugin for pfSense, I have retired the dohservers.txt blocklist and now recommend anyone who needs this functionality to use the DoH feed that pfBlockedNG provides natively. Anyone who continues to have my old feed set up in their firewall to be pulled periodically will be getting a 404 error.
This information has also been updated in my Safer@Home with pfSense book.