(Mindless) The Undead Army and the war crimes it committed other than merely existing.

The CHG, despite how long it's lasted compared to other systems of humanity, is far from unchallenged. On one occasion in 2673, there was a religious terrorist/rebel group that was oddly lacking in support (something about their religion being unpopular or some other stupid nonsense - personally I'm of the belief that any excuse to engage in rebellion is one worth using, even if it doesn't apply to you) and they had a genius idea on how to fix this problem: an army of reanimated corpses! They'd seen tonnes of documentaries about people being brought back to life within 30 minutes of dying without any unfixable neurological damage (just some lost memories, being utterly traumatized, often suffering from mental disorders afterwards, sudden loss or gain of religious belief, etc), so clearly it could work.

Disgustingly enough, it did. The terrorists then claimed to be reincarnations of special individuals in their religion and that they were bringing about the end of Satanic/evil rule for a holy utopia. Yeah making dead things undead does hit quite a few power-fantasy-activate buttons, especially in zealots who thought it would be okay to bring back people who had been dead for several days or even weeks.

In their "oh my glob all I can remember is the fact that I have a daughter not even her name or anything we did together" state (physical weakness was accounted for by cyborgification and stem cell regeneration), most of them were pretty easily manipulated using early and illegal VR headsets before being fully converted into a zealous army, also with those headsets.

In total, there were 500,000 of them when they were unleashed onto the city of Recent York, often killing the very individuals they knew back when they were alive - and even often hesitating or refusing to do so when they had flashbacks to what little they knew of those they killed. Regardless, what of the city's population didn't run away or weren't already members of the religion that the terrorists committed their actions in the name of was killed and turned, after the remaining undead were taught how to carry out the procedure themselves, into more undead.

Luckily for the CHG and, most likely, humanity on the whole, it was around this point that the undead horde was stopped by those from among it. You see, those inhabitants of the city that were reanimated had far more of their memories than those in the initial forces and, unsurprisingly, this led to a tonne of infighting until the undead opposed to the rebels came out on top.

The CHG forces that arrived were very confused by how they weren't being shot at, allowing for these inhabitants to be allowed to live... as weird as that sounds when someone of them had stitching from the bullet holes they died bleeding from... and continue living as normal humans in the cases where this was actually possible. Widespread knowledge of this increased the number of insanely rich individuals that paid to have the personnel and equipment on-hand to reanimate them if they died really quickly, although anyone who wasn't insanely rich was gonna have to make do with the one life or get encountered by an overly-determined ambulance operative like Elmir Solovan.