Rusty Spots, Potassium? Calcium? Magnesium? Deficiency

[RobboWolves]

Alright lads, having some issues week 6 in flower.

Bubble Runtz Tastebudz
Bio bizz light mix
20L Air pots
2 plants under Mars Hydro TS1000 on 100% now
Day temps/humidity 24degrees/50%
Night temps/humidity 18 degrees/55-60%
Advanced nutrients grow/micro/bloom (half strength)
AN Sensizym, B52, Bud Candy, Bud Factor X, Overdrive (1mm per litre, half strength)
Bio Bizz CalMag and BioHeaven

I bought a TDS pen as I was burning plants in early flower TDS in run off was over 2k so flushed out with PH neutral water, got the run off down to around 700TDs for week 4 in flower. I started feeding nutes again throughout week but I appear to be having some deficiencies, I’ll add some photos any help would be appreciated, in determining what the rusty spots are. Thanks.

[RobboWolves]

[RobboWolves]

PH is 6.5

[barney_b]

In my opinion, your VPD was too low for your PPM resulting in your plant not being able to uptake enough nutrient to keep up with those massive buds. That would also explain your high runoff. Only a couple/few weeks until harvest, yeah? Those leaves are toast. They are food. You're going to get some more bud swell and some more fade. Go with it. Embrace it. You've taken them this far and the plant is well equipped to cruise to the finish line.

If my diagnosis is incorrect, it doesn't actually change the inevitable. Would love to hear other opinions.

Well done.
B