“Monitor changes to posts” – doesn’t undo on changes

I have the option “Monitor changes to posts” enabled which correctly adds a redirect if category slug changes.

Eg:
/slug/test-post/
Changes to
/new-slug/test-post/
A 301 redirect is added for /slug/test-post/ -> /new-slug/test-post/

However, the problem/question I have:
If I change the category back to slug, the redirect which was automatically added remains in place, causing problems/redirect loops. What is meant to happen to that old rule in this circumstance? (I know I can manually delete it).