I was playing a normal game of zombies, standard, no LTM or anything. I did complete the main quest but other than that, I was literally just killing zombies the whole time.
When I went to QC to prepare for exfil, I noticed that one of the zombies eyes were blue and that it looked electrified. I then noticed that quite a few of them were like that, and it seemed to happen out of nowhere. Killing one of these zombies would visibly (and audibly) transfer its soul to a nearby "normal" zombie, which then gave that zombie the blue eyes + electrified effect. If there was not a nearby zombie for the soul to attach itself to, it seemed like the game would spawn in one just for that purpose. These zombies lived through the round-changing, and even stuck around during the special rounds with the Klaus's. I have never seen this before while playing and I have played a lot of this map as it is one of my favorites.
The video shows all of this in a lot better context. What could this have been? Was this some weird bug/glitch or something else?