Moss Carpets Float on Top of Water

While I was exploring mangrove swamps I kept breaking root blocks and noticed there was a moss carpet on top so I broke the root block that is supporting it but it kept floating on water.

 

How to Reproduce:

1. Place a waterloggable block in one block high water.
2. Place a moss carpet on top of the waaterlogged block.
3. Break the waterlogged block.

Observed Result

Moss carpet floats

Expected Result

Moss carpet would break and not float