What are the strange yellow mottling of color on m...

Hi mate! Well, you should not give them all that nutrition so early. You're creating some problems that way, over water, over feeding... You should not remove any leaves by now too. the look to small for that kind of stress and they need all leaves at this moment to cacth a good amount of light and develop strong branches and a nice structure. That's a lot of stress you're making them pass. Just water them for a couple days, less lst, try to let them reach a full recovery. The yellow marks on the leaves appear when there was some issues about magnesium and calcium, you need to let the soil dry to avoid all that kind of problems and lack of nitrogen too. But keep going , they will be strong :)

I think there are a couple of issues. First and foremost you are over watering by a lot. Let the pot dry out before watering. Second, with 3 gallon pots there should be no feeding at this stage, what's more you are using quite a lot of stuff, are you even measuring the EC of your feeding?