As far as I understood, from this forum and chats on the game and discord, some players are happily getting double xp from every source while others are getting no bonus at all.
The players who have the bonus xp enabled have absolutely no idea how they got it, and the ones without any bonus don't know how to activate that bonus xp.
So... what's the point of this event? How does it work? How the rewarded players are selected? Why aren't all players allowed to get this bonus?