### 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)

defines += "\n#define SAMPLERS_BINDING_FIRST_INDEX " + itos(SAMPLERS_BINDING_FIRST_INDEX) + "\n";
	}
#ifdef REAL_T_IS_DOUBLE
	{
		defines += "\n#define USE_DOUBLE_PRECISION \n";
	}
#endif
	scene_shader.init(defines);
	
	render_list_thread_threshold = GLOBAL_GET("rendering/limits/forward_renderer/threaded_render_minimum_instances");
	_update_shader_quality_settings();
}
RenderForwardMobile::~RenderForwardMobile() {
	RSG::light_storage->directional_shadow_atlas_set_size(0);
	
	for (uint32_t i = 0; i < render_pass_uniform_sets.size(); i++) {
		if (render_pass_uniform_sets[i].is_valid() && RD::get_singleton()->uniform_set_is_valid(render_pass_uniform_sets[i])) {
			RD::get_singleton()->free(render_pass_uniform_sets[i]);
		}
	}
	{
		for (const RID &rid : scene_state.uniform_buffers) {
			RD::get_singleton()->free(rid);
		}
		RD::get_singleton()->free(scene_state.lightmap_buffer);
		RD::get_singleton()->free(scene_state.lightmap_capture_buffer);
		memdelete_arr(scene_state.lightmap_captures);
	}
}