Not a post-mortem as such, but does contain links to some specific cases of breakage. It’s a nice list of possible failures - not a complete list - and the point is that DNS is fundamental and sometimes involved in unexpected ways.
https://jvns.ca/blog/2022/01/15/some-ways-dns-can-break/
Hacker News not biting on this one, yet.
https://news.ycombinator.com/from?site=jvns.ca