And asset duplication on older console generations. The consoles only had HDDs, and so to ensure a level's assets would stream from disk quick enough they packa

And asset duplication on older console generations. The consoles only had HDDs, and so to ensure a level's assets would stream from disk quick enough they packaged copies of all those assets together. So the exact same game can be smaller on PS5 than PS4 as the SSD makes fragmentation irrelevant. Often the developers also forget to remove unused files and cut content, but I don't think this has a large effect on the game size.