Export with col colonly default plane from blender to godot wrong collision mesh

I tried to export with collision shape option from blender in godot only the default mesh named plane.
The idea was to determine what optimization I have to create objects with this plan and with the resulting collision and get optimization through array versus complex objects with complex collisions that would increase the size of the resulting game.
It seems that the collision is a cube with a size of 0.04 that does not respect the side of the plane and shrinks to a smaller size…
Has anyone tested whether it is the case on other versions of godot and blender that you get a cube collision with dimensions smaller than the size of the plane? Is this a bug or can be fixed?
In a previous version on more complex meshes it worked very well, the collision shape was consistent with the object.

Godot Version

v4.3.dev5.official [89f70e98d]

Blender version and windows OS

version: 4.2.0 Alpha, branch: main, commit date: 2024-03-29 10:43, hash: d174959759e7, type: Release
build date: 2024-03-29, 12:16:07
platform: ‘Windows-10-10.0.19045-SP0’


The collision mesh is the thin blue mesh wireframe on your mesh not the yellow box. The 0.04 is the Shape3D.margin property which is a different thing.

The importer does not use other Shape3D shapes than ConcavePolygonShape3D and I think ConvexPolygonShape3D (I’m not 100% sure about this one) even if more generic Shape3D shapes exist like BoxShape3D or SphereShape3D

… I see later that blue but in the Godot the brown cube say CollisionShape3D. Good answer !