Hey, bro! 👋
It's a phosphorus deficiency, bro! Soon you'll see brown spots at the edges of the leaves where they are currently light! 👆
Maybe you overfed it with Gro, because your leaves are a lush green color. Due to high nitrogen concentrations, phosphorus could be blocked. 👆
During the vegetative stage before flowering, the bloom:grow ratio should be (1:1), but never overfeed your girls with nutrients!
It's easier to fix a general deficiency than a general excess of nutrients! 👆
Good luck, bro! ✊😇