[ghc]

New Englander here. Gotten is normal vocabulary. If it's not used in British English, then it's probably a feature of North American English, since most North American linguistic differences are snapshots of common features of 16th-17th century British English that somehow ossified over here.

Edit: It appears my conjecture was correct: https://www.sarahwoodbury.com/on-the-use-of-the-word-gotten/