A couple of months ago Catalin Cimpanu, one of the (very few) reliable infosec-oriented journalists published this article in ZDNet. It's worth a reading as an introductory material: https://www.zdnet.com/article/dns-over-https-causes-more-problems-than-it-solves-experts-say/ The Dutch National Cyber Security Centre document mentioned in the Catalin's article is here: https://english.ncsc.nl/binaries/ncsc-en/documents/factsheets/2019/oktober/2/factsheet-dns-monitoring-will-get-harder/Factsheet+DNS-monitoring+will+get+harder-v1.1.pdf Regards, Enrique