Minecraft wiki entry for Damage, associated text: In Java Edition, players and mobs take damage if too many entities are packed into the same block space. Specifically, the maxEntityCramming gamerule defines the maximum number, above which a player or mob takes 6 suffocation damage every half-second, as long as that player or mob is pushing greater than that number of other entities. The default max number of entities in one block space is 24. Pushable entities include players, mobs, boats, and minecarts.