Black spots pale leaves

I’ve got two plants going one is a jack and the problem plant is a bubblegum they are both on the same diet of nuts magnesium and molasses it’s my 2nd grow I have these black spots on the bubblegum and it’s progress seems stunted running two mars hydro lights in a small room with plenty of air and rh around 40 ish just curious why the one plant other than a lil droopy is doing good but the other is struggling any help appreciated thanks

Honestly looks like both a P and K deficiency to me. I'd definitely look for a second opinion though. Molasses is pretty high in potassium so if that is the culprit may be a lockout issue. Am I correct that your stems look really purple? Hard to tell in the pics.

Molasses is also really high in Magnesium and Calcium, when you say they are being fed magnesium are you talking CalMag?

Your plants are just underfed and starving. Thats why you have the yellow (chlorosis) and necrotic spot. Your droopy plant looks like it has no drainage, it needs to dry out. Make sure to feed with cal mag every time even a low feeding if you mix in coco. Use a sprayer and spray your plants 2x a day when its dark to bring color back to the leaves with a foliar feed. Use dilute fert and seaweed if you have it.

I’m just using a tea spoon of Epson salt in a gallon of water and giving them that atleast a couple times a week