All items of these eggs can only be exchanged von xingwangs Blog

In this event of the 3rd. anniversary, Psyonix decided to change the format of the event a bit. The format of the in-game currency in this event are "balloons," and you can swap them for various cosmetic items. What will change is the box system. There will be no single boxes of this event or Rocket League Keys decryptors that will be replaced by "Golden Eggs".These Golden Eggs can simply be opened and do not require keys or decryptors. Within them there are 1 of the 60 possible items from the old "Champion" boxes that are no longer available.

All items of these eggs can only be exchanged, that is, they can not be exchanged for normal box items. Apart from all this, a new game arena and a new 3v3 game mode will be added where the positioning of the beacons is different. In fact, it will remind the Rocket League predecessor, Supersonic Acrobatic Rocket-Powered Battle-Cars (SARPBC).