Slabs break fast with pickaxe

Breaking a Slab with an Efficiency 5 Netherite pickaxe breaks it at the same speed as an Efficiency 5 Axe.
I used Efficiency 5 Pickaxe and Efficiency 3 In video

https://onedrive.live.com/?cid=35417825AD9963A7&id=35417825AD9963A7%2117433&parId=root&o=OneUp