Hello! Minehut runs on a server platform named Paper Spigot, this is a popular performance based fork of the commonly used server software Spigot. As it is a performanced based platform, many improvements were added to the base game that help prevent issues like lag, as such experience orbs will merge within a set radius.
This radius can be changed via this setting in the spigot.yml file:
merge-radius:
item: 2.5
exp: 3
See below for a great CFAQ on how to edit the spigot.yml file.