Btw just a tip, if you have a higher temperature allow the humidity to stay higher so she can still transpire at a proper rate, higher temps higher humidity, lower temps lower humidity.
That could also be a potassium excess wich in turn can cause zinc, iron, calcium and magnesium deficiencies.
Check for signs of new foliage developing thinner blades or interveinal chlorosis in newer leaves.
Best of luck growmie and stay lit.