K & maybe P

P deficiency will show a blue hue in leaves - don't see it. K deficiency will cause damage around the serated tips and some chlrosis along the same area etc.. don't see that, either. See some pale leaves low on theplant? looks to be tip-in progresssion. that could be a n-deficiency. Shit ton of leaf. Fairly loose colas.. might be a little weak on light -- need to focus them on a smaller area/smaller plant for better resutls -- also could be genetics-caused. make sure your lights produce enough umol/s PAR for the area of coverage to hit ~35-40 dli without running the light 24/0. If it'sa photoperiod, need to work backward from highest needs -- 12 hour operation. if you need 24/0 in vege, it's not going to work well on a 12/12 schedule later on. 13/11 can work well, but that's only 8% more DLI compared to 12h.

Don't stress it by growing under 24/0. plants need downtime as well. 18/6 is fine as long as the DLI is around or below 40. Above 40 you need supplemental CO2. diary is lacking weeks and feeds. so a guessing game, may want to put more details into next time and that the feeds are you have listed. I don't see how cardboard can provide co2 out of nothing. unless it being broken down it should not be off gassing enough that would be considered significant.

Salt capacity of medium looks to be reaching its limit judging by tips. High ec. Lime green all over with no obvious starting point in normally associated with a alkaline ph skew making alot of micronutrients harder to uptake. Especially iron which above ph of 7 P will bind with iron instead of oxygen. Iron is essential for chloryphyll production and will cause plant to lime green all over due to being unable to replenish chooryphyll efficiently after the rigours of photosynthesis. Temps are a little high keep under 77 if you can , look after those precious tricks and I'd also def lower your humidity so late into flower. A nice cushy 65% daytime can easily creep into the 75 + overnight. Look to hold around 50 55 to really prevent any rot or moisture forming.

Or it could be just deficiencies Which i highly doubt, with all these feedings... But it,s easy to check (mesuare EC or ppm)

My last grow i also hide it in the box xD hehe, nice thinking) - same shit as in question before Why? By look at right plant Mg excess etc By look at left plant Ca excess etc read my answer in other question near urs