[Ka-el]

Spoiler for 255:

Finally it was explained how Sukuna managed to kill Gojo: he used a Binding Vow and forced himself to satisfy three conditions to perform the world cutting dismantle every single time in the future (chant, hand signs and using hands to direct any slash), so that's why he didn't use any of it when he cut Gojo in half, which almost explains why Gojo didn't dodge it.