Kind of hard to tell from those pics but it's not a nitrogen deficiency. I'd say potassium deficiency which is a mobile nutrient and symptoms could start from the bottom. You don't really need to be using calmag with that soil. They use oyster shell as a pH buffering agent and it has plenty of calcium. It also has crab and shrimp meal which are both high in calcium. The Tiger Bloom you're using has an adequate amount of magnesium in it.
I know everyone thinks you need to use calmag but you don't if you're growing in a soil like FFOW that already has enough calcium in it. Too much calcium and magnesium can cause problems with potassium uptake.
This isn't cannabis specific but the principles still apply regarding how calcium and magnesium can affect the uptake of potassium in plants.
"Prophylactic applications of calcium applied as lime or gypsum that are
not based on soil test results could create deficiencies in other positively charged nutrients (cations), primarily magnesium and potassium. These cations compete for limited binding sites (very limited in our sandy soils) on soil particles and for uptake by plants. An example below (Figure 1) demonstrates preferential uptake and availability for a paired soil and plant analysis. The soil analysis indicated high potassium and magnesium in the soil but the tissue test resulted in low potassium and magnesium in the plant. Plant analysis for calcium was sufficient. In this case the tomato plants were in good shape with no underlying conditions such as nematode infestation or soil-borne pathogens to inhibit root function. The preferential uptake is where calcium is taken up by the plant and not potassium or magnesium. Deficiencies of both potassium and magnesium can have significant consequences for plant growth and development."
"The effects of calcium and magnesium on the uptake of potassium were generally insignificant in these tests; however, there were some significant reductions in plant potassium uptake as the calcium and magnesium contents of the soil increased. The effect of increased soil magnesium on reducing plant potassium was especially more noticeable than the effect of increased soil calcium."
You always want to maintain a balance in the soil. Constantly feeding it one or 2 different elements that build up in the soil disrupts the equilibrium. I'm not a soil scientist I just read the results of scientific studies conducted by them and base my conclusions off of science.