What is the best way to raise awareness of a extension upgrade that breaks core fuctionality, e.g. all the menus went away?
I'd like to build out more infrastructure for this.

I've started an Extension Compatibility List which so far has the ability to blacklist an obsolete extension (my original use-case was for merging an extension into core), but it could be extended to blacklist a version of an extension with known bugs or security flaws.