slight nutrient imbalance issue. pH is fine, mayby overfeeding or underfeeding?

If was K deficiency it would present as mobile primarily on old growth. Given K's role in the guard cells its unlikely you see k deficiency with good turgor. Generally when anything effects margin tips as a primary start locale, tells me the plant had a role in where it placed whatever it was that sucked up that caused the dmg.

Could be too little K or something locking it out like too much P. Not too many things start with damage on the serated tips around outside of leaves. An overfeed often causes more than 1 symptom, so i'd lean toward too much K. If soilless/hydro and well below ~180ppm (elemental not ug/l).. this does not apply to soil. different animal with more to consider than just what is in the fertilizer. looks to be slow-moving so don't overreact.. cross reference as much as you can and make the most educated guess. doing the 'wrong' thing just makes it worse quickly.

You have held almost identical environmentals for entirety of flower. 60 rh is ok, but if your hvac is not on point you will at some point run into trouble. As flower progresses the plant releases more and more exudates into the soil, this increases microorganism activity rather drastically, along with the medium gradually becoming more moisture retaining as flower progresses, along with increase micro activity. The more active they become the more oxygen they scavenge from the medium. This leaves less oxygen for plant process. If you have been blanketing same x amount of water, you will need to cut back slightly as flower goes on or increase rate of transpiration by cranking temps. Oversaturation of medium is a problem In flower. Soon as oxygen is low, plant switches from aerobic respiration to anerobic. Releasing lactic acid, carbon acid, ph begins to skew, atp levels drop dramatically. Growth stunts. High ec would be distinctly brown tips. Dmg you see is Oxidative stress in plant leaves, especially near the margins, can manifest as marginal necrosis. Still just a guess though. So best of luck.

Hi also gibt zwei Ursache die ich mit diesen syntome in Verbindung setzte, Die erste und die wahrscheinlichste ist das es zu einer überdüngung gekommen ist, Messe doch mal deinen runoff und kontrolliere dort den PH und EC wert, der PH wert solte zwischen 5.8 und 6.5 liegen und der EC wert unter 2,sonst hast du zu viel Salze im Boden. Dann msut du ein paar mal ohne Dünger Gießen und den PH wert so anpassen das er in dem oben genannten Bereich liegt. Wenn diese aber stimmen dann kann es die zweite Ursache sein. Anfang eines Kalium Mangel aber denke ich eher noch nicht. Hoffe das hilft dir ein bißchen weiter und beobachte wie sie sich entwickelt. Viel erfolg