Before the game, the players on both sides took a knee to honour the Black Lives Matter movement. Before that, English fans booed the Italian national anthem.
After the match -- after England had lost to Italy, after three English players had missed their chances in the penalty shoot-out, three English players who happen to be black -- the dark sickness of English racism erupted.
Social media was vile, even by its own standards. You need no imagination to know what was going on.