perfectly normal at end of flowering... in many contexts. Has development been ~normal? you are 8 or 9 weeks into flower?
Looks a bit glossy if i zoom in, but can't be certain in picture. If that's the case, it's a little burned. Senescence is making it look worse than it is. Ther's probably little you can do. Bright side is that if you irrigate with water only, it'll have plenty stored...
how long is the flower period? that'll need to be considered. You don't want the entire canopy to fade before it is done.