Number one for me has got to be the infodump at the end of “De Other Side,” where Mueh’zala randomly confesses to a bunch of crimes. Pretty sure I actually laughed out loud at the screen the first time I heard that. I half-expected him to add, “And I’d have gotten away with it too, if it weren’t for you meddling adventurers!”
Runner-up goes to the Gorilla Gorge/King Grong story in BfA. The Horde PC goes through a lighthearted storyline liberating peaceful intellectual gorillas and helping overthrow their tyrannical leader. That’s it. It was one of the few Hordeside stories in BfA that was actually just genuinely fun.
But then the story jumps directly from that to “Noble King Grong loves the Alliance and the mean Horde raised him as undead! Oh, and the goblins are enslaving and skinning gorillas!” It’s hard to convey in a summary just how jarring and nonsensical that feels. It’s one part “multiple chapters are missing from this story” and one part “man, the writers are drunk on the villain bat.”