Thinking this is a magnesium deficiency but want to make sure.

9 week old Pai Gow in 5 Gal Fabric Pots using 60% FFOF 30% Coco 10% Perlite.
Temps are 68-75
RH is 40-50%
Water until 20% runoff every 3-4 days but recently 3.
PH is 6.2-6.8
Gave her 10 tbs of Gaia Green 4-4-4 at week 5
Don’t have any cal mag so that’s why I assume it’s a magnesium or calcium deficiency, so I foliar sprayed with epsom salt diluted at 1 tbsp per gallon for magnesium but the leaves still look the same.
Photos here.
Any thought on what this could be, how I could improve?

Will update.

Mixing coco and soil is this result. Both work at different pH and watering practises.

Coco likes around 5.5-6 pH so I would feed at 6 since it’s a soil/coco hybrid thing. Next time it’s best to choose one or the other