Naming an NPC also makes it so that they'll never despawn. Which means when you rename a random zombie in a cave, for instance, that zombie will continue being there permanently, Even though you depart and under no circumstances come back. On the other hand, renamed NPCs can however die, http://how-to-cook-chicken-liver24568.shotblogs.com/how-to-turn-off-nametags-in-minecraft-bedrock-options-21442462