I see this Body Timeout Error frequently, almost every day, but for random VMs. It has been happening for weeks but since it's not consistently the same VM I figured overall I still have good backups. I also back up the VMs in different ways and the others aren't failing. It has more recently been happening with the config backups which should be very short. Previously I wondered if it could be increased network activity that messes with a long backup of a big VM but that would not be the case for config backups.
The failing backups are all network local, just to be clear, I am not streaming this backup to Backblaze or something where internet connectivity might be causing it.