The NPC halfling models in the HA Shake the Citadel are enormous (heads are through ceilings in some places). It happened last night and again today so it's not a one-time thing. It also happens in the base zone of Arx Mentis. While hilarious, it feels like a bug.
This was fixed internally on March 20th and will go out with the April update. Enjoy the giant halflings while you can!