I don't think Harry Maguire would have been called up to the England national team if he was overrated. That's why it might be a bit harsh to say it's exaggerated. He definitely has talent and it wouldn't be right to claim otherwise. However, he is very error-prone and this causes big problems in the teams he plays for.
Maybe that is also the question of many people, why does he still get a place in the England national team, even though in his team he doesn't get a place as a core player at the club. It could be because the two coaches have different views regarding Harry Maguire and of course he is considered good by Southgate. He is a talented player, that's why Manchester United was willing to buy him at a fairly high price from his previous club, but the mistakes he often makes can no longer be tolerated because they are quite detrimental to the team. Maybe he will change and become better if he can find the problem that caused him he often make mistakes.