Some spam, tracking and ad servers are blocked at the DNS level on my network. For me it is therefore undesirable that programs use their own DNS.
I disabled Trusted Recursive Resolver in Firefox. In
network.trr.mode = 5
Look at https://gist.github.com/bagder/5e29101079e9ac78920ba2fc718aceec what this code means.
For comments, please send me an e-mail.