Excellent find, Masamune1004.

Data for 1.20 has been fixed, so until 1.21, it looks like we'll all just have to imagine that some errant Amalj'aa dropped a Zahar'ak coffer key while on a stroll through Shposhae...and then some other Amalj'aa found it there and brought it back to Zahar'ak...where you killed him.

(It looks like the help text for the Copper and Gold Zahar'ak coffer keys have the same problem. We'll be sure to fix those as well.)