I saw the release list for 1.31. You aren't credited with 5 of your electrum/score points after an arena win. So, every Bronze win gets cheated out of 5 electrum. That's how you can win 3 but lose 2.
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Yes, I confirmed it. You get cheated out of 5 electrum and score for each bronze arena win. That's a bug to be fixed in 1.31.
So, if you "win" 3, you actually lose 2.