In new Challenge Match feature, Deck Image of the selected deck is shared with my opponent when I clicked "Ready" button.
Not only this reveals some deck information in a out-of-game way, it spoiled our experience of popping out surprising cards in the game.
To avoid this, I need to use unrelated card image for all of my decks.

I hope this "deck image feature" is removed as soon as possible, or at least, let me disable this feature.