Over feeding?

Raising rh, all other factors the same, would decrease transpiration/drinking. So has the heat gone up lately? If that resulted in a higher VPD, then the plant would drink more. looks like you are essnetially soilless at this point and providing nearly 100% of all plant needs after 7 weeks with 40/60 soil/coco and d i'm sure some perlite or similar which cuts the pre-charge of the soil significantly too. If fertigating each time, simply compare ppms of some likely offenders (leaf chart as a guide). If fertigeting every other or every third irrigation, then divide by appropriate number to average ppms over that stretch. K-def - no idea where this starts from experience. Willl just say for my climate and other relevant local variables, 180-200ish is the point at which i very rarely see a toxicity over many weeks of fertigation. K-tox is also possible with burnt serated tips around edges. It progressess differently from there. chlorosis and spots etc. Not seeing spots, but this looks fairly early, eh? Anyway, significantly higher or lower would point toward that as the cause, but not any samller deviations. I tend to run a higher vpd than one should, so my numbers are probably a bit lower than someone with a lower average vpd, but again these are probably 5-10% swings in any normal, healthy context. too much P is another possibility. Another one i've never seen firsthand. 40-70ppm with religious 10% runoff in a soilless context hasn't caused any problems over long-term. Seen a grower on yourtube go 90-100ppm and plants look fine. So, if this is the case, you'd really have to be gassing it. all we can ever do is consider how we've fed (ratios and concetration plus whatever soil provides) and eliminate possibilities seed on a leaf symptom chart. It is not exact. Diagnosing visible leaf symptoms alone is a guess at best except for a few incredibly obvious ones. Could le tthis progress and it might be more obvious, or if considering how you've fed over the last weeks to month+, eliminate the less likely options and make a more educated guess.

Well, to me it looks like you're showing heat stress up top and maybe a pH issue on the lower stuff. You might have salts building up at the roots. I'd check there first, maybe do a flush.