Zombified piglins will not make anger noises when targeting a non-player entity.

My guess is that this is related to the new changes to neutral mob anger. Through testing, it seems that most neutral mobs (endermen are a notable exception) making angry noises are determined by the AngerTime nbt tag being greater than 0. These mobs, however, don't use nbt to determine which mob they are targeting, meaning these sounds/appearances are no longer triggered. Wolves had the same issue before it was fixed.