Fixed matches are real, of course, but nobody expects them in the big leagues. In a big game like the Community Shield. I also would not like to undermine the efforts of Crystal Palace because they worked hard for the win in the second half.
Matches that are fixed have been reported in the past because the accomplice was caught and due to the unusual nature of the game play. You will find them in leagues that many people, including the media, are not interested in, that is, lower leagues where the wages are low. The players and officials may become accomplices here because their earnings are low and the gain from carrying out the act is high financially.
The big leagues have stricter regulations to catch any fixed match even before it happens, and if it does slip, the penalty is very stringent for those involved. Besides, players and officials in big leagues earn way more than those in lower leagues; therefore, the promise of any higher financial gain will not even catch their attention.