In that case, check the resolution of the mesh distance field that represents the she shell. Since it’s a lot of thin geometry, it could easily be light-leaking from the SDF’s volume texture being too low-res to represent it. set the mesh distance field resolution in the settings to 2.0 or higher, but this does come with a memory cost.
Either that, or use HW ray tracing if available. Either way, it should help.