Interesting effect. It does look very voxel-y. I'm not a video game developer at heart, so I can only guess how it was implemented. I doubt NeRF models were involved, but I wouldn't be surprised if some sort of voxel discretization was.
If you think about how they created this from the POV of the game creation pipeline, then that probably is the way. If this is done by creating a shader on top of "plain old" 3D assets, then aside from the programmers/artists involved with creating that shader everyone else can go about their business with minimal retraining. There probably was a lot of content to create, to that optimization likely took priority over other methods of implementing this effect.
