Direct answer

Mob despawn distances affect natural spawning and farm rates. They are distinct from entity activation range and simulation distance.

How to check it

  1. Identify which category of mob is accumulating: hostile, passive, named, tamed or plugin-created.
  2. Compare player locations with the world’s configured soft/hard despawn ranges in the relevant version of Paper.
  3. Use /paper mobcaps and /paper playermobcaps to observe natural spawn pressure where supported.

Example: When a farm becomes unproductive after changing despawn distances, inspect player position and mob cap behavior before increasing spawn limits to compensate.

What to change

Change only the relevant mob category, and retest spawn rates and unloaded/loaded locations with representative players. Investigate persistent mobs separately.

Software and version notes

Named or otherwise persistent mobs can be exempt from normal despawn. Old YAML examples may not match the current per-world configuration layout.

Verify the result

Check that farms still produce expected drops, passive animals remain as intended and natural mob caps recover after players move.

References