Has there been any update to the site I'm not aware of? Where can I read more about what changed?
The changes are described in this Stack Overflow blog post: New post notices: Improving feedback on Stack Overflow questions.
The change affects all post notices, including moderator notices, post locks, migration notices, bounty notices, and every single type of close notice. The changes apply today on Stack Overflow, the Stack Exchange Network, and the Basic/Business tiers of Stack Overflow for Teams (Enterprise Teams will see the change in an upcoming release).
We have some guiding principles that we’re applying as we improve any feedback loops in the Q&A system, including post notices, going forward. Wherever possible we will work to provide better, actionable guidance for all users that helps everyone use the platform successfully while reducing room for public shaming.