Hiyo. Plz notice the 10/30 pics. Should be about...

Heyo chef so ill agree with athos on this looking like a calcium issue, its on leaves that are being exposed to the lights which is classic calcium...however a couple other things stood out to me, if youre using water from the tap not bottled ro water theres usually a good amount of calcium available. I also used the fox farm trio and it worked great, however i eventually added a flower booster of theirs similar to what you show, the low N and very high PK and while 2 of my plants further in flowering did well, 1 did not and displayed these similar calcium looking deficiencies even though i was using a calmag supplement. So i later found out that excessive amounts of potassium display almost identical symptoms. Unfortunatey into flowering usually the affected leaves wont recover. But you seem to have many healthy leaves still. I hope you can get to the root of the problem, and definitely check the ec/ppm if you're able like athos mentioned. Keep up the battle and happy flowering. ✌️