1. Facebook defaulted a bunch of posts to public, when they should have been something else.
2. Users posted a bunch of things with this unexpected default
3. As one part of fixing the bug, Facebook changed all posts made with the unexpected default to private. They were attempting to undo the damage.
Some of the posts they made private probably were intended to be public, so they made things worse for certain users.
1. Facebook defaulted a bunch of posts to public, when they should have been something else.
2. Users posted a bunch of things with this unexpected default
3. As one part of fixing the bug, Facebook changed all posts made with the unexpected default to private. They were attempting to undo the damage.
Some of the posts they made private probably were intended to be public, so they made things worse for certain users.