RBGanswered grow question 9h ago Okay so, slowed growth can be a few reason of things. Could be locked out due to salt build up. If you haven't flush your plant with pH neutral water without any nutrients or additives, if you're using a 10gal pot, 10L is enough to do this.
Could be root problems, as you can't see because its in soil you can use a Root cleaner to fix this issue. I run rdwc so I need pythoff to keep root rot from forming.
Could be your nutrients intake or watering ( not getting enough or too high E.c )
Could be a calmag issue but doesn't look like it.
Remember your light is shared, the bigger plant will take more lighting which in return will give you slower growth
Could just come down to genetics even if its the same strain/breeder it could have popped out a different pheno from the one its originally meant this