There is a flip side to this - is vim encrypting this data it keeps forever? If I delete something I consider sensitive, I might unwittingly be recording that presumed-deleted piece of data to my user profile somewhere to be deleted never.

Vim's persist undo is disabled by default, perhaps for privacy reasons. edit: I see sebzim4500 got there first.

* https://news.ycombinator.com/item?id=49867678

* https://bastian.rieck.me/blog/2015/persistent_undo_vim/

That doesn't justify its deletion, it might justify warning the user, but unconditionally deleting data not owned by the app shared with other apps?

Stop looking for post-hoc justifications for behavior that is clearly wrong.

How could you possibly encrypt it in a way that holds water? Any attacker who cares enough to get your undo file can also get your undo keys, unless you want to wire a whole system of undo-now-requires-password-auth-with-MFA

Not really since the feature is opt in