In Temple of Kotmogu, orb holders get a debuff which reduces healing taken by 5% per stack. However, this debuff is not reducing absorb shields. The flag carrier Focused Assault debuff in Twin Peaks, Warsong and EOTS does reduce both heals and shields, so the Kotmogu orb debuff is most likely bugged.
When I look the debuff up on wowhead, it shows a “Mod Absorb Taken %” effect, which seems like it is intended to reduce absorb shields, but it currently doesn’t work.
It’s not a huge problem, but it does make healers which use absorb shields (disc priest mainly) overpowered on this map.