Some times when you complete a achivment that gives the battle pass XP on arena when you are on tutorial the game just dont let you clarim the reward that happend alot to me 40% of the times i created a new account that bug happend when i played arena on the tutorial
thus stop creating new accounts and play on the same one
When you are f2p and you want to play New decks its the only option bruh its that or wait 5000 billion years to get enough dust for a new deck