Football appears to be a lot more tactical these days, and I suspect it affects a lot of players in a similar way - where they're drilled into playing in a particular style.
Alexander-Arnold has some astonishing skills, but he plays in a team which is almost built around him and Robertson, with half the team covering in defence, and the rest pulling everyone into the centre, so that they have time to run up and down hitting crosses. Put him in the England team and he's just not the same player.
Foden looks like he has no-one to pass to when he plays for England - he wants to receive the ball, pass and run, get it back, pass again - but for England IF he finds someone to pass to, they'll often go off and do something else!
Southgate doesn't seem to be tactically astute enough to get them all playing together, so has made the best of it with a safety first approach, and hoping that someone will do something special at the other end of the pitch.