### 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 (pipeline_rd != prev_pipeline_rd) {
			
			
			RD::get_singleton()->draw_list_bind_render_pipeline(draw_list, pipeline_rd);
			prev_pipeline_rd = pipeline_rd;
		}
		if (xforms_uniform_set.is_valid() && prev_xforms_uniform_set != xforms_uniform_set) {
			RD::get_singleton()->draw_list_bind_uniform_set(draw_list, xforms_uniform_set, TRANSFORMS_UNIFORM_SET);
			prev_xforms_uniform_set = xforms_uniform_set;
		}
		if (material_uniform_set != prev_material_uniform_set) {
			
			if (material_uniform_set.is_valid() && RD::get_singleton()->uniform_set_is_valid(material_uniform_set)) { 
				RD::get_singleton()->draw_list_bind_uniform_set(draw_list, material_uniform_set, MATERIAL_UNIFORM_SET);
			}
			prev_material_uniform_set = material_uniform_set;
		}
		RD::get_singleton()->draw_list_set_push_constant(draw_list, &push_constant, sizeof(GeometryInstanceForwardMobile::PushConstant));
		uint32_t instance_count = surf->owner->instance_count > 1 ? surf->owner->instance_count : 1;
		if (surf->flags & GeometryInstanceSurfaceDataCache::FLAG_USES_PARTICLE_TRAILS) {
			instance_count /= surf->owner->trail_steps;
		}
		RD::get_singleton()->draw_list_draw(draw_list, index_array_rd.is_valid(), instance_count);
	}
	
	if (should_request_redraw) {
		RenderingServerDefault::redraw_request();
	}
}
RenderGeometryInstance *RenderForwardMobile::geometry_instance_create(RID p_base) {