However these are most likely not related to nametags and despawning and should be tracked individually as their own report with context and if possible reproduction steps. Thanks you! The bug When a few mobs were named with a name tag, some would occasionally despawn....
When a dolphin picks up an item, it gets permanently marked as persistent, as with all mobs that can pick up items. However, dolphins pick up their items only for a brief moment so they can play with them. If a dolphin ever touches an item, it cannot despawn in the future. ...