Sick Plant [Completed] Brown spots and yellowing leaves... mid to late flowering

@ThePerfectTree-IRE, welcome to Percy's glad you made it. Your spots and leaf issues are caused by either a Calcium or Magnesium or both deficiency. These are elements that are slow moving and they take awhile before they showing a problem, so by the time you see them on the leaves it's too late, it's been happening for a while. During flower and the use of strong LED's will produce this deficiency if steps aren't taken to increase the supply. I start ramping up Cal/Mag in mid veg so I have the plant stocked up ahead of time. The good news is it won't kill the plant, if your using salt based nutrients then you can add some, don't foliage spray with Epsom since your in flower, but you can water in some if your in super soil. The  leaves won't recover they will get worst, but don't pick them off. She obviously needs Cal/Mag and she has some in her leaves that's why she sucking it out. When the leaf is dead and falls off that's when she's done with it and you can remove it, but not until then. All of her leaves are food storage for her. She has them stocked full so that if something happens and she can't get food from the soil, she can pull it from her leaves. So leave the leaves alone, we don't smoke the leaves. There's not enough time to fix her and she's not fixable, she's in flower and that's all she's concerned with, your harvest won't be affected by this. Good luck man. 👍