Getting a loss when someone on your own team leaves is correct, feels bad but it's the only way to do it - but what train of thought leads to penalizing the winning team? Like, I don't know of any decent game that does that (only dumpster fires stuck in the 2000s like SFV), why would you ever think that's a good idea? You punish leavers individually to discourage the practice, but nothing should change for any of the remaining players.