these brown parts are mainly at the upper buds and the bud which are affected smell a little rotten.
I checked for insects but there are none. Temperature is also normal as well as humidity. It only affects 1 of 4 plants.
I'd have to say maybe a burn. I'd flush her good shes real green too. She should smoke just fine. I've had so many harvests and this happens. It's just part of growing sometimes we live and we learn. It could even be cal mag deficiency if your growing under LED. Hope this helps growmie.