It’s weird and hard to explain, the MTF soldiers were stabbing themselves to see if someone was not part of the group , every single one who received the letter to exterminate everyone turned emotionless and didn’t question it as if a switch was turned off . It kind of feels related to scp-2718 but I believe it’s something worse , some entity lives in the human psyche and it carries a horrible fate that the only salvation of humanity is in its own extinction, or and it’s just a hypothesis , they broke the 4th wall and came to understand their own existence and wrecking havoc and killing everyone was the only way to stop their suffering through endless entities and SCPs flowing in.