The main issue they were trying to fix had existed. It sounded like the release with the fix included a Pull Request which introduced a new bug that affected syncing. This second bug was easy to isolate and fix, but it caused a lot of trouble for 24 hrs. I'm sure the dev who created the Pull Request is feeling pretty embarrassed this week.

Disclaimer: I didn't verify anything I'm saying here. I'm piecing together what I heard on the Simply Bitcoin podcast with my own experience with bugs & upgrades on my node this week.