### 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)

reflection_probe_count = p_reflection_probe_instance_count < (uint32_t)MAX_RDL_CULL ? p_reflection_probe_instance_count : (uint32_t)MAX_RDL_CULL;
	for (uint32_t i = 0; i < reflection_probe_count; i++) {
		reflection_probes[i] = RendererRD::LightStorage::get_singleton()->reflection_probe_instance_get_forward_id(p_reflection_probe_instances[i]);
	}
}
void RenderForwardMobile::GeometryInstanceForwardMobile::pair_decal_instances(const RID *p_decal_instances, uint32_t p_decal_instance_count) {
	decals_count = p_decal_instance_count < (uint32_t)MAX_RDL_CULL ? p_decal_instance_count : (uint32_t)MAX_RDL_CULL;
	for (uint32_t i = 0; i < decals_count; i++) {
		decals[i] = RendererRD::TextureStorage::get_singleton()->decal_instance_get_forward_id(p_decal_instances[i]);
	}
}
void RenderForwardMobile::GeometryInstanceForwardMobile::set_softshadow_projector_pairing(bool p_softshadow, bool p_projector) {
	use_projector = p_projector;
	use_soft_shadow = p_softshadow;
}
void RenderForwardMobile::GeometryInstanceForwardMobile::_mark_dirty() {
	if (dirty_list_element.in_list()) {
		return;
	}
	
	GeometryInstanceSurfaceDataCache *surf = surface_caches;
	while (surf) {
		GeometryInstanceSurfaceDataCache *next = surf->next;
		RenderForwardMobile::get_singleton()->geometry_instance_surface_alloc.free(surf);
		surf = next;
	}
	surface_caches = nullptr;
	RenderForwardMobile::get_singleton()->geometry_instance_dirty_list.add(&dirty_list_element);
}
void RenderForwardMobile::_geometry_instance_add_surface_with_material(GeometryInstanceForwardMobile *ginstance, uint32_t p_surface, SceneShaderForwardMobile::MaterialData *p_material, uint32_t p_material_id, uint32_t p_shader_id, RID p_mesh) {