Any widespread yellowing or leaf necrosis is not normal at any point during veg or flower. Pics and more info on your grow needed to pin point your issue.
Could be a number of things maybe just plain water for next couple of feeds no nutes could be salt build up but need pics and more info am still pretty new to it
hey brother from another mother, so the best thing to do here is to post a pic and give a lil more info so the experts can do a better diagnosis on your girls and everyone here is not trying to kill everyone here just for saying the wrong thing..