leaf issue

Is it just on the side of the plant that is close to the pot rim? As it goes through the light cycle leaves will raise and lower, from lights on to lights off. It could be rubbing on the rim. Now if you throw some air flow from a fan in there and you can get leaf damage that looks like this. Could be a nute issue, but if it's just those leaves on that side, id hold off on making any drastic changes. See if it progresses or if it just stays on the part close to the rim of the pot. If it stays there on those leaves and show on any other parts of the plant, its damage from rubbing. PS careful of advise given on here. Some may be right, some will be way off base, myself included. Im not always right either. Most people on here generally try to help, but some on here are trolls! Just my thoughts, Best of Luck! Happy Growing!

more likely light K deficiency

What's done is done, so long as it's not progressing, There is a lip on the top of your pot, from the soil to the top of the pot, which will act like a small buffer zone of high relative humidity (RH). While high humidity doesn't directly cause mechanical damage to cannabis leaves, it creates conditions that can promote mold and mildew growth, hinder transpiration, and negatively impact nutrient uptake, all of which can lead to various forms of leaf damage. You have been adding a lot of Fish from day 1, and more organic matter in the soil requires more oxygen. In plants, nitrate NO3- is the preferred form of nitrogen for uptake and utilization. While plants can also absorb nitrogen as ammonium NH4+, Biobizz Bio-Grow contains 4% nitrogen, it includes 0.464% ammonium nitrogen, 0.2% nitrate nitrogen, and 3.536% organic nitrogen. Organic nitrogen is not directly NO3- (nitrate) or NH4+ (ammonium) it needs to be broken down into NH4+ then NO3-. When ammoniacal nitrogen (NH4+) in the soil exceeds 20% of the total nitrogen (N), several issues can arise, primarily related to toxicity and imbalances in the soil ecosystem. Specifically, high levels of NH4-N can inhibit root growth, reduce nutrient uptake, and potentially lead to nitrogen toxicity in plants. Furthermore, excessive NH4-N can disrupt the soil's microbial community and increase the risk of nitrogen loss through leaching and volatilization. Between organic grow nitrogen and fish nitrogen, you are feeding hardly any NO3- that the plant can actually uptake right away. The rate at which nitrogen is converted in the medium is highly affected by pH, this is called nitrification. Not much of that is happening when you're running a pH of 6.0. Nitrification can occur at a pH of 6, but its rate is significantly reduced compared to optimal pH levels. While nitrification is generally most efficient around pH 7.5 to 8.0, it can still happen at a pH of 6, although at a much slower pace. At pH 6, the rate of nitrification can be as low as 10-20% of the rate at pH 7. the process of converting ammonium to nitrite and then to nitrate, requires oxygen. It is an aerobic process, meaning it needs oxygen to occur. Not going to be much of that in that pot. Get her going, correct ph feed her what she needs, or stick to mineral fertilizers that are already broken down, and try to keep organic matter to 5% total. Good luck

Consider underwatering or nute burn