### Godot version

4.1.1

### System information

windows 11, mobile renderer

### Issue description

On Mobile Vulkan renderer, the clear color is 50% lighter than expected

See steps to reproduce and Minimal reproduction project below.

The box and background have the same color on Forward+ and compatibility, but not on Mobile
happens also in runtime on exported project, not only in editor preview

Images of the same scene from
compatibility:
![compatibility](https://github.com/godotengine/godot/assets/11915378/a874fa86-c16f-43ef-aed7-c2066b770ac1)
Forward+:
![forward](https://github.com/godotengine/godot/assets/11915378/e416f9a6-dfd4-4c47-bbc2-b552ca58f83c)
Mobile:
![mobile](https://github.com/godotengine/godot/assets/11915378/e28e2db8-f7c3-47e2-8c0a-44ce937c9270)


### Steps to reproduce

 - add a CSGBox3D with "unshaded" shading, and albedo of #545454
 - add environment with Background = Custom color and color of #545454

Box and background are not the same color

### Minimal reproduction project

[bg_color.zip](https://github.com/godotengine/godot/files/12174822/bg_color.zip)

RendererRD::MeshStorage *mesh_storage = RendererRD::MeshStorage::get_singleton();
	RendererRD::ParticlesStorage *particles_storage = RendererRD::ParticlesStorage::get_singleton();
	GeometryInstanceForwardMobile *ginstance = static_cast<GeometryInstanceForwardMobile *>(p_geometry_instance);
	if (ginstance->data->dirty_dependencies) {
		ginstance->data->dependency_tracker.update_begin();
	}
	
	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;