I mentioned a while back that editing older posts can easily cause category mentions to break because the structure has changed. The syntax for subcategories is different, so each category that has become a subcategory is affected by this.
Now it’s not just a few category mentions that are broken in posts that were recently edited - it’s most of them, in many posts. I guess posts were rebaked recently.
For example:
I know we’re supposed to only report things we can’t fix ourselves, but it didn’t seem practical to go through all the wiki posts now and update them manually. I can’t fix the other posts anyway. So maybe a bulk replace for all categories that are now subcategories is the better solution.