It’s also kind of ironic because Charlie Hunnam is also British, but his character, Raleigh Becket, was American and had an American accent in the original Pacific Rim.
Thankfully John Boyega was allowed to make some changes because that’s the kind of thing that could have sounded weird to audiences.
As John Boyega told The Hollywood Reporter, some words just don’t flow well with his accent.
So it is possible that some of the dialogue in the script was still left over and originally meant for him.