### 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)

if (p_sh9) {
		if (lightmap_sh == nullptr) {
			lightmap_sh = RenderForwardMobile::get_singleton()->geometry_instance_lightmap_sh.alloc();
		}
		memcpy(lightmap_sh->sh, p_sh9, sizeof(Color) * 9);
	} else {
		if (lightmap_sh != nullptr) {
			RenderForwardMobile::get_singleton()->geometry_instance_lightmap_sh.free(lightmap_sh);
			lightmap_sh = nullptr;
		}
	}
	_mark_dirty();
}
void RenderForwardMobile::geometry_instance_free(RenderGeometryInstance *p_geometry_instance) {
	GeometryInstanceForwardMobile *ginstance = static_cast<GeometryInstanceForwardMobile *>(p_geometry_instance);
	ERR_FAIL_COND(!ginstance);
	if (ginstance->lightmap_sh != nullptr) {
		geometry_instance_lightmap_sh.free(ginstance->lightmap_sh);
	}
	GeometryInstanceSurfaceDataCache *surf = ginstance->surface_caches;
	while (surf) {
		GeometryInstanceSurfaceDataCache *next = surf->next;
		geometry_instance_surface_alloc.free(surf);
		surf = next;
	}
	memdelete(ginstance->data);
	geometry_instance_alloc.free(ginstance);
}
uint32_t RenderForwardMobile::geometry_instance_get_pair_mask() {