Our Entity rules explained

How are Mobs on the server automatically moderated to reduce large farms and lag?

Unfortunately, Minecraft is primarily a single-player game. Therefore, everything is designed around single-player worlds. If we left single-player rules with 40+ players online, the server simply wouldn't be able to handle the load and ultimately be unplayable and crash.

So we have to implement rules for mobs, entities and how they can spawn and exist in the world.

The first thing you must understand is that mobs aren't moderated per-chunk. They are moderated in a 5x5 chunk area, your view distance in-game (2 chunks between each entity)

For example, if you have 10 villagers within a single chunk, you won't be able to spawn anymore within your view distance. See the below diagram for an example. 10 villagers are in the central green chunk, so no villagers can exist in the red chunks. The outer green chunks are far away enough from the 10 villagers for more villagers to exist, however they will not function unless they are in you are in your stimulation distance. 

Keep in mind that you try to bypass the limit, the extra entities over the max limit will automatically despawn. Anyone trying to bypass the limits will be punished accordingly. 

Entity Limits

You can only have the maximum amount specified here within your render distance in-game, 3 chunks apart - 2 empty chunks between them.
If you wish to make multiple villager trading halls for example, they must be more than 3 chunks apart.

Passive Mobs
Skeleton Horse: 3
Zombie Horse: 3
Donkey: 3
Mule: 3
Giant: 1
Pig: 10
Sheep: 10
Cow: 10
Chicken: 10
Squid: 3
Wolf: 5
Mooshroom: 10
Snow Golem: 5
Ocelot: 10
Iron Golem: 5
Horse: 3
Rabbit: 5
Polar Bear: 5
Llama: 5
Parrot: 5
Villager: 10
Turtle: 10
Cod: 5
Salmon: 5
Pufferfish: 5
Tropical Fish: 5
Dolphin: 2
Cat: 8
Panda: 3
Trader Llama: 3
Wandering Trader: 3
Fox: 3
Bee: 10
Strider: 10
Bat: 0
Axolotl: 5
Glow Squid: 3
Goat: 10
Frog: 10
Tadpole: 10
Allay: 10
Camel: 10
Sniffer: 10

Hostile/Neutral Mobs
Elder Guardian: 2
Wither Skeleton: 5
Stray: 10
Husk: 10
Zombie Villager: 5
Evoker: 5
Vex: 5
Vindicator: 5
Pillager: 1
Ravager: 1
Illusioner: 5
Creeper: 10
Skeleton: 10
Spider: 10
Zombie: 10
Slime: 5
Ghast: 5
Zombified Piglin: 10
Enderman: 10
Cave Spider: 10
Silverfish: 10
Blaze: 10
Magma Cube: 10
Ender Dragon: 1
Wither: 1
Witch: 10
Endermite: 3
Guardian: 10
Drowned: 10
Hoglin: 10
Piglin: 10
Zoglin: 10
Piglin Brute: 10
Shulker: 10
Phantom: 5 

Other Entities
Painting: 5
Arrow: 5
Splash Potion: 10
Item Frame: 10
Glow Item Frame: 10
Armor Stand: 10
Evoker Fangs: 3
Boat: 5
Minecart: 5
Minecart Chest: 5
Minecart Furnace: 5
Minecart TNT: 1
Minecart Hopper: 10
Minecart Mob Spawner: 5
Ender Crystal: 4
Hopper: 20
Piston: 20
Sticky Piston: 20
Observer: 20
Redstone torch: 16
Primed TNT: 10
Firework: 10
Spawner: 4
Boat Chest: 5 

Farming Limits
Bamboo: 40
Cactus: 40
Kelp: 40
Melon: 40
Pumpkin: 40
Sugarcane: 40
Twisting Vines: 40
Weeping Vines: 40