m0useanswered grow question 3 years ago the one plant seems to have some mild nitrogen toxicity, the lower leaves on the right plants are darker then the healthier looking plant on the left. The new growth on the right plant is a lemon lime green as well, I forget what causes that.
Could just be variants expressing themselves in its different phenotypes if their controls are all the same, feed, temps, water, RH, PH, ect.
If it gets worse take action based on the symptoms its displaying and start a new question with updated info and photos.
good luck