N#4 got some NuteBurn, pretty sure...
leaf will not recover. Try mixing your nutrient-water a little bit more between plants to avoid the nitrints to stick in the bottom and overfertile the last watered plant (since the others are not shwoing any stress). Also consider stop usig the rapid start since it is a third Nitrogen Source in your mix.
Don't worry about the burned leafs, they would be waaay low soon... They should fall off anytime anynway😁
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