So, there are two things here:
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Getting an edge by having access to more information about the game world than the typical player, forcing everyone to look up this data to keep an even ground and altering the player experience. That seems legit, at least in intent, as it's a multiplayer competitive game. If it were single-player, I'd say that players should be able to choose whether to look the information up or not, but here one player's actions affect another.
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Ruining upcoming surprises by releasing information about things that have not been activated yet. That seems like the developer's fault. If you want to distribute something to players that you only activate at a set time, then send it out encrypted and only send the decryption key out when the surprise is due.