My original thought was Marcel wave (1) but Duckduckgo also gave me finger waves along with the other images, and I think that's more likely for what one would call Yoongi's hair. (2)

(1) Marcel waves loom large in Arthur's family lore. "After financial reverses," as Grandma Flo said, her parents bought a Marcel wave machine and set up shop, with great success. The story didn't include what they did when the style changed.

(2) He's on the cover of the May Korean edition of Marie Claire, and his hair there looks much more wispy than wavy
https://twitter.com/marieclairekr/status/1645381204475265029/photo/1

I am discontent with my current hair, but I can't figure out what to do with it. Rummaging around, this is from 16 years ago, curly but not wavy. I don't think I could get it to do that again, and the mask straps that go around my head would mess with it anyway
https://lauradi7dw.dreamwidth.org/69604.html#cutid1