Approximately midnight UTC, December 7th, I noticed that the "Help: Setup / Hardware / Performance Issues" forum had disappeared without a trace. The topics and posts that had been within that still existed, but the forum itself was gone. I managed to manually restore that single item from a backup. However, about an hour ago I was notified that a user account was missing as well. I checked, and this user had existed prior to this glitch.
So, given the fact that it was more than a single database row missing, I made the decision to restore the database from a previous backup. Luckily, the good backup was from 5AM UTC on December 6th, so we only lost about a day's worth of data.
Any changes to groups or posts that were made from 5AM UTC December 6th to midnight UTC December 8th will need to be redone.