Question about Vertex Color Error Factor in "Evolving a Legend: Bringing Halo to Unreal Engine 5" talk

Hey!

In this talk by Halo studios at Unreal Fest Chicago 2026 Greg talks about how they rely on Vertex Data for material layers, and mentions “Vertex Color Error Factor” to control the popping effect that happens with nanite meshes and vertex color based masks.

Is there any information on this, and is it implemented into UE by default or is this totally custom?

Thanks in advance for any input.