Beginner question

This is nitrogen toxicity, it has nothing to do with light changes. Different strains require different feeding schedules...........indicas can handle heavier feeding and sativas like less feeding.

I would need a bit more information.. I'm going by intuition. The clawing leaves are more often caused by an excess of nitrogen or an excess of water (the light change doesn't matter). Are you letting the soil dry out well between waterings? Is there good air circulation? Anyway, for me, it's a root problem if you answered no to the first question... If it's a root problem, it could be rot or something else.. the solution would be to let the soil dry out well, and if it doesn't improve, cut the rotten roots and restore the soil by adding mycorrhizae. Since you have fabric pots, you could try smelling the bottom of the pot to see if it smells rotten... On the other hand, if you said you're letting the soil dry out well, then the problem could be an excess of nutrients, so a good flush with water and you can start over slowly... I hope this helps, it's a shame to see a plant like this... and as I said, these are just assumptions because I don't know the plant's history.