problem

Not necessarily a lack of calmag could be a lockout, really help to have a pic of entire plant, if it's a true nutrient deficiency alone then it will present on old growth if it's a lockout it may be more spread over the plant even on new growth which can be tricky to diagnose. Necrosis is next level to chlorosis, nute that presents interveinally like the in old growth is mg imo. Gluck.

Intervenial necrosis. Mg def.

Yeah il second that she needs Calmag and about 2 mll for next 2 feeds, you don't want to wait till you can see improvement because you will be over doing it then especially in soil.. Good luck pal

hey 👋 calmag every watering, 2ml/l till its corrected