Whenever people have something to say about his vocals, they usually bring up his 2015 - 2016 covers or some cursed Fake Love/vocal line performances. Like don't y'all know people can improve? Some really love bringing up the "bad technique" argument, just to bash his vocals. Since debut, his technique wasn't as bad as people keep on telling. Even today, I wouldn't call his technique the best in kpop but it is definitely above average. He doesn't have much of a breathy voice now as he did back in 2015. But even back then, he used to sing that way to suit BTS songs.
He has improved a lot since 2019. He has a great command on his voice. He can sing in various styles. As for vocal technique, you can't sing the ON bridge, if your singing technique is even below average. Only good vocalists can do so. Most vocalists (even the good ones) can't play around with their voices like Jungkook and still sound great.
would just like to add this for the thread:
This is Jungkook's predebut audition clip.
Not tryna bash a 13 year old, but his performance wasn't really that great. Then why do you think loads of kpop companies wanted him to sign their label? It's bc singing can be improved through technique and practice. Even after global fame, he's still trying to improve himself which shows his passion for singing. And that's something we all can appreciate.