Piglins, Hoglins & other mobs have a custom stepping subtitle

I was having fun playing with Piglins and spawned other mobs (such as zombies) and then noticed that the piglin stepping sound has a different subtitle (rather than Footsteps).
Edit: I spawned Hoglins too and noticed the same issue.
Edit 2: I was digging thru the game files and noticed that other mobs have a custom step subtitle