When this arose with my plants not long ago I had to adjust all my DLI, PPFD and my VPD...Light intensity and length of time the plant is exposed to light was my major factor, I had to dim my light, raise the ficture and change my light cycle a bit,..I also reduced water and changed the temp and HR and slowly adjusted those values back to baseline which evenly lead me to my DLI and PPFD counts...Download tent buddy it has a par reader and DLI calculator and also has a VPD calculator as well that app definitely helped out many times...If your PPFD is high and you DLI is high I would adjust that first, take 24 hours to notice a difference, it that doesn't trouble shoot the other issues one by one