For me it's the back of my hair.
The front (bang section) of my hair grows WAY slower than the rest of my hair. It's almost depressing how slowly it grows, as compared to say, the back. It's only now touching the top of my lip
erplexed
My theory is that this is the only part of my hair that was constantly subjected to abuse pre-journey....daily flat ironing, more frequent relaxing (it was my my weave leave out), constantly unprotected, etc. Maybe it's just never recovered