Hard to tell with just a pic and no info. First thought…overwatering…soil looks really wet
Yeah I’m with @Poseidon1 Looks over watered. How much an how often. Also do you have good drainage.
Plastic pots can be difficult. Dry her out. Weigh her by hand. Fill her up. Lift. You now know wet dry weight.
I have 10 plants and I water them all the same way this is the only one that looks like this
I have 10 plants and I water them all the same way this is the only one that looks like this. And are in the same type pots
I just watered before the pic and I water every week and spray neem oil
Overall plants look good, Curious how much are you watering an how often. 
There’s your culprit Neem oil. Throw that nasty stuff away. It burns plants if mixed too strong especially with lights on and ruins buds. You got some kind of fungus or bugs?
I don’t mix it with the water an I don’t spray it on the leaves I use it lightly bc of the smell I have seen few gnats but they have gone away there is relatively new soil besides the soil the roots were in I just transplant 3 of them into bigger pots the other are lovely