hi, i'm just a noob making diagnose, so don't bite if i'm wrong,
i'm still learning, thank you.
roots are visibly bursting from the top or circling the pot, i guess not.
squeeze the pot; a healthy root system should still have some give in it whereas a pot-bound plant feels tight, specially on soil i think.
roots growing through the drainage holes or matted at the base. can't say from picture alone, look not really bound.
foliage should be green and not yellowing. looks there are some problems.
but then i read this.
Root rot can be identified by the presence of soft, brown roots. The root system of a healthy plant should be firm and white. But when soil is soggy, fungal spores multiply and the fungus starts to spread. Not to soggy?
hmm prob this, As plants get close to harvest, it's normal for them to show signs of a nitrogen deficiency. At that stage, you want the plant to direct all of its energy into the fruit or flowers rather than growing new leaves. Adding some grow feeding would help here if it is the problem.
but then if you got lots of dead roots Sensizym or something like that would help i guess.
Hope i wansn't far away with diagnose, Pro dudes correct me if i'm wrong. I have spoken
lolz