Incorrect, sir.
[…] We will soon adjust the behavior of creatures in most dungeons to make it significantly more difficult to endlessly snare and kite enemies. Additionally, we will implement a reduction to group XP earned when there is large disparity between player levels in the same group. […] We plan to roll out these adjustments to Burning Crusade Classic realms at the same time as the Joyous Journeys XP buff.
https://us.forums.blizzard.com/en/wow/t/1267344
They’ve said nothing about Joyous Journeys being attached to pre-patch.
beginning a few weeks before the 3.4.0 Pre-Patch