Could be a lockout if your PH is off?It’s the only one like this every other one are good how can I fix
Could be a deficiency if you are locked out.
Or could just be sensitivity to what it is being fed. Different phenos of same strains can sometimes have different nute tolerances. Try 1/2 strength nutes and make sure your run off PH is in the 6.5-6.3 range. 6.3 is ideal.