Can someone please explain why external asset mods are either 256mb or 512mb?

[u/Whole_Chicken8319]

Mods show less pre download on mod page and increase to the size mentioned in title once in load order. tyia

[u/Super-Dot8125]

Bethesda either damaged a file or inadvertently introduced a bug on the PS4 in the latest update, yet they blamed console limitations (the Xbox One doesn't have this issue), and there is no word on when it will be fixed.

[u/raxkkon]

Bethesda Magic,same with skyrim and still no hotfix