Firefox can now send your DNS Requests over DNS and your really should use that option. Your DNS Requests are normally send over clear-text UDP visible to your Provider and everyone who is able to intercept your internet traffic. This means almost everyone is able to see what pages you visit. DNS over HTTPS changes that by encrypting your DNS queries.
Go to about:preferences#general
I will do some research on what DOH capable DNS to use and report back with it. Btw. this ridicolous twit of an association of UK ISP’s inspired me to encourage everyone to use it. Also it made me comment on twitter, first time for ages. Calling Mozilla an internet villain for protecting peoples privacy. WTF.