### Godot version

4.2.dev 5ee983188de97ae027f9b9c1443438063f708a7e

### System information

Windows 10 - Compatibility renderer 

### Issue description

When running a VR project sky contribution is not working in the compatibility renderer:

![image](https://github.com/godotengine/godot/assets/1945449/7aa19569-95c8-41a2-913b-37b81f4728a7)

It is working fine in normal mode. Can be worked around by setting sky contribution to 0 and providing an ambient color.

### Steps to reproduce

Try any project with a proper sky setup in XR, just switch to compatibility renderer.

### Minimal reproduction project

I'll try and create an MVP soon that can be used without XR hardware, but for now this can be used:
https://github.com/BastiaanOlij/godot_openxr_demo
}
	
	switch (ginstance->data->base_type) {
		case RS::INSTANCE_MESH: {
			const RID *materials = nullptr;
			uint32_t surface_count;
			RID mesh = ginstance->data->base;
			materials = mesh_storage->mesh_get_surface_count_and_materials(mesh, surface_count);
			if (materials) {
				
				const RID *inst_materials = ginstance->data->surface_materials.ptr();
				uint32_t surf_mat_count = ginstance->data->surface_materials.size();
				for (uint32_t j = 0; j < surface_count; j++) {
					RID material = (j < surf_mat_count && inst_materials[j].is_valid()) ? inst_materials[j] : materials[j];
					_geometry_instance_add_surface(ginstance, j, material, mesh);
				}
			}
			ginstance->instance_count = -1;
		} break;
		case RS::INSTANCE_MULTIMESH: {
			RID mesh = mesh_storage->multimesh_get_mesh(ginstance->data->base);
			if (mesh.is_valid()) {
				const RID *materials = nullptr;
				uint32_t surface_count;
				materials = mesh_storage->mesh_get_surface_count_and_materials(mesh, surface_count);
				if (materials) {
					for (uint32_t j = 0; j < surface_count; j++) {
						_geometry_instance_add_surface(ginstance, j, materials[j], mesh);
					}
				}