No Peaceful Despawn

Have you ever accidentally switched to Peaceful difficulty? If so, you probably remember how all hostile mobs suddenly vanish! Iron farms break, the XP grinder loses its endermite, that enderman digging dirt around itself in a boat seems to disappear, and worst of all—the zombie that picked up your best netherite sword is gone without a trace!

That's exactly what this mod is for! When Peaceful mode is enabled, mobs won't despawn, though their spawning will still stop (by the way, you can activate mob spawners or infested blocks using the command /gamerule doPeacefulMobSpawners).