Big Asset Bundle size

I am packing one Scriptable Object instance into asset bundle. On my disk, the scriptable object has 1kb. However, when I pack it into Asset Bundle, the final bundle has size of 4.5MB, why?

I am sure that only that file is packed, since its listed in bundle info.

Any advice?

Maybe the Scripting object is referancing itself somewhere and it gets recusively serialized, just a thought…

If scriptable object references other audio textures etc. and those assets are not bundled as their own label. they will be included as part of the scriptable object. (Same goes with prefabs btw)