### 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)

framebuffer = rb_data->get_color_fbs(RenderBufferDataForwardMobile::FB_CONFIG_FOUR_SUBPASSES);
		} else if (using_subpass_transparent) {
			
			framebuffer = rb_data->get_color_fbs(RenderBufferDataForwardMobile::FB_CONFIG_THREE_SUBPASSES);
		} else {
			
			framebuffer = rb_data->get_color_fbs(RenderBufferDataForwardMobile::FB_CONFIG_TWO_SUBPASSES);
		}
	} else {
		ERR_FAIL(); 
	}
	p_render_data->scene_data->emissive_exposure_normalization = -1.0;
	RD::get_singleton()->draw_command_begin_label("Render Setup");
	_setup_lightmaps(p_render_data, *p_render_data->lightmaps, p_render_data->scene_data->cam_transform);
	_setup_environment(p_render_data, is_reflection_probe, screen_size, !is_reflection_probe, p_default_bg_color, false);
	_update_render_base_uniform_set(); 
	RD::get_singleton()->draw_command_end_label(); 
	
	RID radiance_texture;
	bool draw_sky = false;
	bool draw_sky_fog_only = false;
	
	float sky_energy_multiplier = 1.0 / _render_buffers_get_luminance_multiplier();
	Color clear_color = p_default_bg_color;
	bool keep_color = false;
	if (get_debug_draw_mode() == RS::VIEWPORT_DEBUG_DRAW_OVERDRAW) {
		clear_color = Color(0, 0, 0, 1); 
	} else if (is_environment(p_render_data->environment)) {
		RS::EnvironmentBG bg_mode = environment_get_background(p_render_data->environment);
		float bg_energy_multiplier = environment_get_bg_energy_multiplier(p_render_data->environment);