It looks like a deficiency imo but I don’t know enough to tell. Strain is chronic widow it is 3 weeks in to flower. It is in a 5 gal pot of happy frog and ppm runoff is 950-1050 ph is 6.4ish. It is being fed open seasame tiger bloom and cal mag
Sometimes you get colors, sometimes it has to do with the nutrient line, temperatures, and often times it’s just the genetics.
So doesn’t look like anything that could harm it?
As long as you’ve checked ph going in, and run off, and are feeding properly, if everything is in line that I would say genetics.
“If only the parts getting hit by immediate, direct lighting are affected (purple, red, or yellow leaves), while the rest of the plant remains healthy and normal in color, it is very likely a lack of phosphorus“