### 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)

RID sky_rid = environment_get_sky(p_render_data->environment);
			if (sky_rid.is_valid()) {
				sky.update_radiance_buffers(rb, p_render_data->environment, p_render_data->scene_data->cam_transform.origin, time, sky_energy_multiplier);
				radiance_texture = sky.sky_get_radiance_texture_rd(sky_rid);
			} else {
				
				draw_sky = false;
			}
			if (draw_sky || draw_sky_fog_only) {
				
				sky.update_res_buffers(rb, p_render_data->environment, time, sky_energy_multiplier);
			}
			RD::get_singleton()->draw_command_end_label(); 
		}
	} else {
		clear_color = p_default_bg_color;
	}
	_pre_opaque_render(p_render_data);
	uint32_t spec_constant_base_flags = 0;
	{
		
		if (p_render_data->directional_light_count > 0) {
			if (p_render_data->directional_light_soft_shadows) {
				spec_constant_base_flags |= 1 << SPEC_CONSTANT_USING_DIRECTIONAL_SOFT_SHADOWS;
			}
		} else {
			spec_constant_base_flags |= 1 << SPEC_CONSTANT_DISABLE_DIRECTIONAL_LIGHTS;
		}
		if (!is_environment(p_render_data->environment) || !environment_get_fog_enabled(p_render_data->environment)) {
			spec_constant_base_flags |= 1 << SPEC_CONSTANT_DISABLE_FOG;