Though the moment itself isn't shown, Gojo Satoru eventually fulfils the grim duty assigned to him over a decade prior, executing his former best friend and his 'one and only', Geto Suguru. Traditionally, a sorcerer's remains are handed over for cremation, often entrusted to allies like Shoko. But in Geto's case, it is implied that Gojo can't bring himself to follow through. He neither delivers the body nor burns it.
This moment of hesitation becomes the catalyst for everything that follows. Geto's corpse, left intact, is seized by Kenjaku, who uses it as a puppet to orchestrate countless deaths, the resurrection of the King of Curses, and the unraveling of jujutsu society itself. Gojo's inability to let go of his friend sets into motion the Shibuya Incident, the Culling Games, and ultimately leads to his own death, struck down by reincarnated Sukuna exactly one year after he killed Geto.