Nutrient or light issue? Let me know

It's mean they will start pre flower stage, and when leaves grow bigger they will get better, if not Then is Magnesium btw look like you have light stress move ur light higher or dim it check PPFD and DLI 😎

If you use Epson salt mix 1 tsp to 6L of water should be enough and do so for a couple waterings

You have a slight magnesium deficiency Magnesium is the nutriment most crucial to photosynthesis. It is at the center of the chlorophyll molecule, thus giving the plant its green colour. Magnesium is also responsible for aiding the process of moving nutrients throughout the plant, especially phosphorus. It is more likely to appear in flowering as it plays a vital role in maturing the buds/flower. As a Mobile nutrient, Lower leaves first begin to yellow as veins remain dark green, creating a striped pattern. In severe cases, the leaf will dry up on the edges and curl inward. Can be caused by: • Improper/low pH level • Nutrient Lockout • Cold root temperatures (Under 18C) For Coco: Ensure Coco has been buffered with Ca/Mg. Without buffering, Ca and Mg deficiencies are more likely to occur. Organic Solutions: • Dolomite Lime (Raises ph in acidic soils and has calcium and magnesium) • Organical Magic • langbeinite Inorganic Solutions: • Epsom Salts (Magnesium Sulfate) add to soil or foliar spray • CalMag Additives

You have PH imbalance throwing sulphur off. Epsom salt will solve this.. You can add to soil & use it as a foliar spray. 150-200ppm added ES to tap. 6 point 7 ph soil 5 point 5 coco water.

Check your run off pH .

A problem with fertilizers, if it is Coco it is worth shedding, if it is earth it is worth reducing the dose