From her biography I’d take a guess she has dual-nationality, US/UK, but I could be wrong.
I just had this happen again. I had no idea that Carrie Coon was Thanos’ female warrior minion Proxima Midnight in Infinity War, or at least that was her voice and face. Her voice is so distinctive I should have known.
My understanding is she did not enjoy the experience and that is one reason her alternate version has no lines in Endgame.
She has stated she turned down coming back for Endgame when they said she wouldn’t get a raise. I find that kind of tone deaf when it was a very small role, one that nobody recognized her in and it’s a role she was easily written out of. No one was going to see Endgame to see her. She wasn’t in a good position to bargain.
By the same measure, though, it’s not really a role that does much for her career, so there’s not much reason to do it except for the money. If the money is low enough, it might not be worth her time to fly out to the recording studio (possibly multiple times - Marvel is infamous for doing tons and tons of reshoots on their films) at the rate they were offering.