The Manchester United centre-back excelled at the tournament, with his finest performance coming in the memorable 2-0 victory over Germany at Wembley.
But since returning to club duty for the 2021/22 season, Maguire has found the going a lot tougher.
The 28-year-old's struggles have been evident for all to see and in the 4-2 loss to Leicester City on Saturday, he was absolutely woeful.
Maguire was at fault for three of the Foxes' goals on the day, which makes Ole Gunnar Solskjaer's decision to rush him back into the team after an injury lay-off all the more questionable.
And just to rub salt in the wounds, one football fan on Twitter has ruthlessly mocked the United captain's start to the campaign with a rather eyeopening video compilation.
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Take a look at the footage here...
Video: Fan mocks Maguire's poor start to the season
Misplaced passes, lapses in concentration and clumsy fouls have sadly been commonplace in Maguire's displays so far in 2021/22.
United really need him to buck up his ideas on the pitch, especially with games against elite-level opposition coming thick and fast over the next couple of months.
The Red Devils host Atalanta in the Champions League on Wednesday, before a meeting with high-flying Liverpool on Sunday.
If they're to enjoy success in one or both of those games, Maguire needs to rediscover the form he showed in an England shirt over the summer.
You certainly wouldn't put it past him doing just that and United legend Gary Neville was eager to remind people not to overreact with regards to the defender's recent sub-par showings.
“Maguire is overrated? No, Maguire is a fantastic player," the Sky Sports pundit said on Instagram Live.
“Maguire wasn’t ready yesterday, he was nowhere near being ready for that match. I think he was thrust back in because of Varane’s injury. Maguire was well off it yesterday.
“But I think he’s the right type, Manchester United need more like him.
“Maguire’s not good enough? We’re on the wrong path here if we’re now starting to say Harry Maguire is not the right type of signing.
“I think Harry Maguire is the perfect type of character for United. I think he’s performed well since he’s come to the club.
“Yesterday he was miles off it, he was nowhere near at the level in terms of fitness-wise and we’ve all been there as players.
“But this is certainly not the time to start throwing the baby out with the bath water.”