More detail in this article: https://www.bleepingcomputer.com/news/security/lets-encrypt-...

Official statement from Let's Encrypt: https://community.letsencrypt.org/t/2022-01-25-issue-with-tl...

Might be relevant to some:

https://forum.netgate.com/topic/169404/statement-on-letsencr...

Previous HN discussion: https://news.ycombinator.com/item?id=30082286