This was my fault. I gave them permission to do extra extends, but I forgot to tell all the players that I gave them permission.
For anyone wondering, I gave them permission to do extra extends because the map was keeping the server alive. We had just finished a tryhard session, we had tryhards on, and we had an active motivated leader. In the image below, you can see that after deadcore ended, the server died (average went from 41 to 28). This just delayed the crash.