Pogba style of play is more suitable in the Italian League, Pogba plays little slow, and the Italian League also adopts a slow game. The English Premier League is famous for its hard game and relies on physicality, it is difficult for Pogba to develop the game because of the different stretches.
I think Pogba can adapt well to the Serie A league because they played in Juventus previously. When Pogba was a Juventus player, they were supported by many skilled players and he was given the full trust of the coach. In this situation, he has high confidence and is free to move anywhere he wants in the midfield line. It is easy to improve his game (performance) because he has a good mood. While in Man United, he can't get the same support as in Juventus, too much pressure in Man United. That's why he can't play as well as in Juventus. So, I think it is not about the characteristics of the league only, but it is about the support from the team as well.