********* DISCLAIMER ********:
**Note, I goofed on the colors for the Yena / Chaeyeon part. Should be Yellow/Blue Mint.
My Twitter Thread isolating vocals: https://twitter.com/hyotaey...
This is what I hear. I’m too lazy to make those fancy color coded lyrics.
The intro is without a doubt Yujin. If you think the second verse is Yujin, then you're agreeing the first verse is Yujin, because it's the same voice. Jonas is a man with an English accent, the verses sound nothing like a man with an English accent to me. He is not singing in this song at all.

The Wonyoung/Chaeyeon and Chaeyeon/Yena parts are what I’ve heard, but I’ve heard Chaeyeon/Eunbi as well. I thought I heard Nako at one point, but I feel like J Line isn't in this song at all, unless they're in the chorus somehow. Their voices aren't detectable in verses.
This is for fun, so fun debates are welcome. I posted this mostly because I want to see how close I am when the official line distribution does come out.