### 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)

}
	
	for (int i = 0; i < (int)p_render_data->instances->size(); i++) {
		GeometryInstanceForwardMobile *inst = static_cast<GeometryInstanceForwardMobile *>((*p_render_data->instances)[i]);
		Vector3 center = inst->transform.origin;
		if (p_render_data->scene_data->cam_orthogonal) {
			if (inst->use_aabb_center) {
				center = inst->transformed_aabb.get_support(-near_plane.normal);
			}
			inst->depth = near_plane.distance_to(center) - inst->sorting_offset;
		} else {
			if (inst->use_aabb_center) {
				center = inst->transformed_aabb.position + (inst->transformed_aabb.size * 0.5);
			}
			inst->depth = p_render_data->scene_data->cam_transform.origin.distance_to(center) - inst->sorting_offset;
		}
		uint32_t depth_layer = CLAMP(int(inst->depth * 16 / z_max), 0, 15);
		uint32_t flags = inst->base_flags; 
		if (inst->non_uniform_scale) {
			flags |= INSTANCE_DATA_FLAGS_NON_UNIFORM_SCALE;
		}
		bool uses_lightmap = false;
		
		if (p_render_list == RENDER_LIST_OPAQUE) {
			if (inst->lightmap_instance.is_valid()) {
				int32_t lightmap_cull_index = -1;
				for (uint32_t j = 0; j < scene_state.lightmaps_used; j++) {
					if (scene_state.lightmap_ids[j] == inst->lightmap_instance) {
						lightmap_cull_index = j;
						break;