A bit confused....help?!? Back leaves

BLACK/YELLOWING LEAVES 9 WEEKS INTO FLOWERING. growing Tahoe og "10 week flower time". Started flushing stage.... is thats whats causing this?, im guessing that....my first grow. hi heat round 84.f lights on and low hum. 30% also.... battling the "desert summer" heat. everything else it perfect ie: lights, vent, co2 ext.. tent growing.
let me know Rollitup Fam

Natural necrosis of the leaves. the budz are sucking all the nutrients stored in the leaves out and into the budz. My plants are at week 9 too and look even worse than yours. Nothing to worry about.

If you are running c02, they will tolerate higher temps.

Nothing you can do now nutrient wise but it does look like a deficiency.