Originally posted by Astner
Here's the full explanation of what happened.- Jujutsu Kaisen ch. 236
I'm not really sure what to make of it. It's a new ability he learned, and it seems a bit more sophisticated than his normal space-cutting slashes. But there you go.
It sounds a bit like 'I learnt not to target Gojo, but instead, target the piece of reality within which he was, which I then cut'. Like an AoE attack that bypasses directed defences.