@ollivehead Unfortunately, there isn't a way to download pervious versions of these playlists.
I recommend creating a feature request for your suggestion if you'd like to see that option added to the service.
This being said, you can always create multiple copies of the playlist without having to worry about them updating.
To do that moving forward:
Open the Featured Playlist you wish to copy and tap the ellipsis to the right of the play icon to reveal a menu.
Tap Add to Playlist to create a new playlist, or to add this featured playlist to an existing one.
Hope this helps!
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