With a hotfix that is now live, we’ve made the following adjustment:
Experience granted to players in dungeons is now standardized, and does not change with the size of the player’s party.
This standardized experience value is equal to what the leveling player would have previously earned in a 5-person party.
Going into the pre-patch, dungeon experience was tuned around the expectation of full parties. However, we saw that taplist loopholes in combination with pre-patch changes to dungeon scaling revealed some extreme leveling tactics by fewer than 5 players. We want dungeons to remain lucrative, and to be a valid alternative to questing and other experience sources, rather than to overshadow them.