Firstly, with nitrogen deficiency leaves are clawing differently - whole leaf is flat but tip sharply turns down at almost 90º.
Secondly, "1ml/L BioGrow in 600ml water" Is almost twice of the recommended value for soil - I think leaves distortion is caused by over feeding.
It's difficult to say why only one plant got affected.
Maybe it got more feeding solution,
maybe it has less light than others,
maybe it was a weaker one from the beginning.