Basically, Korean server (which for some reason announces this stuff a lot in advance) released the following statement (text translated/transcribed by Krasnayazvezda, US server)

We are sorry to inform you that the Super Pershing will be removed from the stores of all servers around the world upon the request of headquarters.
Thus the planned discount of the Super Pershing (note : local event for Korean server only) will be cancelled according to this.
We'll let you know about the details regarding the Super Pershing within a few days.

We apologize you for the abrupt change of the details of the specials.
We'll do our best to provide you better services in the future.
Thank you.

SS: So much fuss over one wrong frontal armor angle....