How is this still an issue?
At the bottom of that PR is a comment by @balloob - Remove hardcoded DNS servers by fenichelar · Pull Request #56 · home-assistant/plugin-dns · GitHub
We make the decisions we do because with Home Assistant OS we are offering a solutions to users that works, for users that want to focus on about home automation, not system administration.
…
If you’re interested in doing DNS stuff, probably Home Assistant OS is not for you. Consider using a Supervised or Container installation.
Except, if you use Supervised it’ll break your install periodically because there’s no way to stop it auto-updating, which is also apparently for the benefit of users, despite breaking things left-right-and-centre: How to stop supervisor auto-update? - #18 by john-arvid
The whole thing is a false dichotomoy anyway - you can have the “user friendly” default of using fallback DNS, and auto-updating and still have a config option to disable it.
I get that there are design decisions that have to be made, but it really is quite frustrating when your home automation won’t remain stable because of those decisions - bugs happen, but you expect they’ll be fixed at some point.