The docs for ladders never actually explain how winning and losing works.
Let’s assume that you are at 100th place and you challenge the person at 50th. Before that game ends you also challenge the person at 60th. You win the 100-50 game, moving you into 50th. What happens if you then lose the game against the person who was 60th?
I haven’t played in OGS ladder but I think ladders generally work the same. I don’t think when the games start have any bearing on it, only where you and opponent are when the game ends and who wins. The guy at 50th that you beat drops to 51st and you take 50th. If the 60th place guy beats you then you drop to 51st and he takes 50th. If you win, nothing changes.
The intended behaviour is that nothing happens. During the recent upgrades, there have been some time periods where this would move the winning 60th person on place 50 and you on place 51.
People use this feature to get back into ladders after timing out by winning any currently running games as well.