Seven fastbuds strains

I hope linking to other sites here is OK. Referencing this site https://howtogrowmarijuana.com/marijuana-symptoms/ it looks like Phosphorus Deficiency. The ability for the plant to uptake Phosphorus is dependent on PH, Temp swings, ect. Is your temperature gauge able to log or track min/max? Your PH and overall temp look good. Whats the PH of your run off? Might have some nute build up in the soil?

there is a defoliation method wich is to take out healty leaves, this will suposedly signal the plant that leaf production is not viable and they will therefore invest more energy into the buds. If the ph issues are solved and she isn't killing the leaves herself anymore then i would cut, if they are still eating away their own leaves then i would leave them in place so the plant can pull out all the nutes she needs from that leaf before disposing of it herself. Its up to you in the end. I defoliate during flower, not everyday but i take some shit out during flower out of necessity but if you can keep the leaves there its best if you do so, they can act as a buffer for future issues. The rule i belive it's: Defoliate only if there is a clear benefit to the plant.