Mozilla has experimented with DNS-over-HTTPS (DoH) for the past few months. The intention is to fix a part of a DNS ecosystem that isnt up to the modern, secure standards that every Internet user should expect. Initial tests of DoH studied the time it takes to get a response from Cloudflares DoH resolver. Soft rollout to a small portion of users in our Release channel in the United States will begin this week and end next week.”]
Source: https://blog.mozilla.org/futurereleases/2018/11/27/next-steps-in-dns-over-https-testing/