If a player leaves in Stadium, and you wait the usual minute and a half, you can, as usual, leave the match without being penalized. However, as long as the match continues (aka as long as any of your teammates are still in the match), you cannot queue for games (for Stadium or any other game mode).
If this happened in regular game modes, you could at least let your teammates know about the bug so they’d leave. However, there’s also a bug that doesn’t grant the win to the other team if your entire team leaves, so you have to see the match through.
And you can’t even just stay AFK, because the game punishes you if you do.
It’s making people not want to play Stadium. What’s the point in playing if I then have to spend 10-15 minutes where all I can do is walk out of the spawn room and die?