In this kind of events, fans of the losing team are usually REQUIRED to leave significantly earlier, for security concerns.
The police don't want different fan groups exiting the stadium at the same time, so as they don't come together in large numbers outside of the premises.
On the other hand, the fans of the winning team are required to remain on their seating location for a pretty long time after the game. It's why whenever you see some stupid meme image that says "respect to the fans of x-team that were still on their stand cheering for their team, an hour after their team won", it's bullshit. The police kept the fans in place and didn't allow them to leave... so obviously, to entertain themselves, they spent the time cheering and celebrating.