I know this is SUPER late BUT i just found this photo.. 

I know this problem but i've been searching it everywhere since i first heard about it..

Now i found it.. I pity Yongguk oppa.. 

He sacrificed for the whole team.. His hair and eyebrow had grown back.. Because at that time, One part of his eyebrow AND his hair was burnt but i think it grows back.. heh^^

anyway.. Thats all!! annyeong~^^