Just gave them a small trim to let some more air in as you recommended, didn't want to go in all guns blazing though so I will go back in a few days and give them another light trim again. Thanks for the advice folks.
Hi pal,
I have also seen this with cold temperatures, if your using LEDs then I would assume you have cooler temperatures.
IMO plants look like this because:
1) overwatered
2) starting signs of becoming root bound (pot too small)
3) unhappy because too cold.
You already mentioned that it would not be overwatered. Your pots look big enough and the other plant of similar size appears happy with the pot size.
That would lead me to assume they are not happy with the temperature or have experienced recent cold temperatures
occasionally cooler temperatures can lead to the plant not drinking as much which causes overwatering.
Put a temperature gauge next to the root zone and on the same floor as your pot and see what your getting.
Depending on the genetics some plants can tolerate higher or lower temperatures so they may not always react the same despite being in the same environment.
Wish you all the best with fast recovery. Having problems when you are just going into flower can be very stressful