Many deficiencies, notably calcium, nitrogen, potassium and phosphorous, basically chronic under feeding.
Each and every plant will have its own nutritional reqirements, even seeds from the same packet/strain, and just because some plants are doing ok with what you are feeding them, does not mean it will be ok for every plant that you have.
Also waiting this long before asking for advice is a mistake, they will be much harder to rescue now, than had you asked a few question weeks ago when the problems first started!