People were leaving after the third Denmark goal went in. At that point, across the stadium it would have been hundreds of people leaving with a good half an hour left.
By the end around half of seats were empty as you can see in the pic I took.
Brian Kerr referenced on the wireless the exact same thing. After the third goal he remarked that he was surprised that the best fans in the world were heading for the exits so early.
People are perfectly free to leave these events whenever they like and it doesn’t give some plonker who insists on staying glued to his seat for 90 minutes on a point of principle the right to criticize them