Issue with Brep/plane intersection and contour: nonplanar curve outputs

Hi,

I am having weird results in a brep/plane intersection and with contour in GH.

I also tried contour (in Rhino) and got similar results: nonplanar curve outputs in the top and bottom:

Any ideas why this is happening?

Attached is a GH file with internalized geometry.

Info about the breps: they are generated form 2 curves (top and bottom) lofted.

Section.gh (22.2 KB)

a tolerance matter.
go to file properties units and use a tighter tolerance. recompute the gh definition after.