Your clips in Deck 1 are still in layer 1, and 2
but I see how you could expect these to move with the layers.
are quite independent from the decks
Decks are just a collection of your clips in rows and columns.
Creating a new layer will only affect the clip layout of your current deck, other deck clips are not affected.
I think this is the behavior you see.
Keeping the decks independent from layers allows you to load decks from other compositions into your current composition. Unfortunately, this comes with the downside of layer changes only affecting the current deck.