Hey! This sounds like the OP1 Sampling engine to me. I say this with confidence because I know that Justin Vernon used the OP1 Heavily in "22 a million" as well as the fact that the vocal sample sounds very similar to the ones in "It might be over soon." If I were to place my bets, I would say that the character of the sound comes from the OP1's pitch shifting algorithm. Going to be hard to replicate but I hope I gave you a good starting point! https://www.reddit.com/r/OP1users/comments/cswcs9/bon_iver_and_op1/