There's truth to this during later flowering, but since writing the comment I have figured out that I was wrong.

The reason for my yellowing leaves is pH is too low. I use a pH adjusting fluid for tap water to lower it, and didn't know that the nutrient feed I'm using lowers it even more, so after I suspected it might be pH I tested and found it that this is the problem my plant is having.

Right now I'm in the process of adding high pH water to try to raise up the soils pH.

In many cases yellowing during the plants vegetative stage is indicative of overwatering. Things can get complicated with cannabis cultivation 😂