Yellowing/Browning on Upper Leaves in Late Flower

Hi there.

I have 4 GDP plants flowering in a tent (second grow, first tent grow). They’re on day 72 since the flip. About a week ago I noticed the upper fan leaves on one of the plants yellowing from the base of the leaf moving toward the tips. There are also brown spots within the yellow areas. Some of the sugar leaves are yellowing as well. It’s slowly spreading. All 4 plants are getting the same feed but this is the only plant exhibiting symptoms.

Any guidance would be much appreciated. Here’s the setup info, and pics are attached.

SETUP

STRAIN: GDP Feminized Photo from ILGM
AGE: 72 days since flip / 62 days since pistils
ENVIRONMENT: Indoor Grow Tent (4’ x 4’ x 7’)
MEDIUM: Royal Gold Tupur (70/30 coco/perlite)
CONTAINERS: 5-gallon fabric pots

CURRENT NUTRIENTS:
CALiMAGic: 1.5 ml/gal
GH Flora Micro: 1 ml/gal
GH Flora Bloom: 4 ml/gal
GH Liquid Koolbloom: 4 ml/gal

WATER SOURCE: RO
WATERING FREQUENCY: Hand-water 2x daily to at least 20% runoff
INFLOW EC/PH: 1.1 EC/6.0 pH
RUNOFF EC: 1.5 EC
LIGHTS: 600w LED dimmed to 490w
LIGHT DISTANCE: 24”
LIGHT SCHEDULE: 12/12
LIGHTS-OFF TEMP/RH: 74-76F / 55-60% RH
LIGHTS-ON TEMP/RH: 78-82F / 50-55% RH
VENTILATION: 6” AC Infinity exhaust/Two 6” fans above canopy/Two 6” fans below canopy

I would be flushing her now no more feed she looks like she’s coming to the end of her cycle the fan leaves are always the first indicator she’s near end I wouldn’t worry at all man looking great nice fat dence buds

Uhm
See the flower in the bottom left?
That is probably what they should all look like at this point
You have nute burn and possibly you we’re late on a water or two
Just guessing based on my own mistakes
I would ride it out at about half what you are feeding and try and nurse them to the end
No cal mag either
But do not flush you could use more maturity time
That’s my thoughts
Only you know for sure how it went
Any issues with light height?

WELCOME TO RIU

Almost looks like an iron deficiency or light burn.

5