Shes now turning red and fatning buds. Shes yellowing dont now if its light stress(her lst is 27/28c, vpd about 1.2 day 600 night and ppfd about 600 and i event gave her so much CO2 now) color changing, string vent or senescense
Your plants are sucking up mobile elements from the leaves for the flowers.
So it's a combination of metabolic stress, maturity and nutrient demand. Watering and lighting of course could affect that.
Main thing though, they are maturing and trying to pump shit to the flowers.
Hey there family.. If your light manufacture chart tell u how far to hang it then u adjust it for max PERFORMANCE.. Those leaves kinda look like not enough water of not regular watering ... Then if you're using nutrients check your mixture is only good for a week after you mix it.. Then maybe you need to feed full strength.. ..i think it's not enough watering/water.. your temperature could also be too hi/hot ..hope you have an air flow/fan....good luck. Nice size harvest looking like😎😎😎