World download size doesn't include resource and behaviour packs

When downloading a world from a realm that has any addon, resource or behaviour pack applied, the downloaded file size is bigger than the world file size, creating a misleading download progress bar.

In the attached screenshot, I have a new world that the game says is 2.8MB, but with packs, is 136.5MB. Since it is higher than 136.5MB, it creates a confusing progress indication, particularly for those on slower connections.