After skimming through I did not see the answer. Here is what I have found.
https://www.blackdogled.com/lst
Leaf surface temperature,
If you are using spectrum specific lighting like LED the leaf has a lower temperature in itself, in turn lowering the transpiration rate. Calcium is immobile or "passive" and requires transpiration to be brought to new growth. Lack of transpiration = Lack of immobile nutrients I.E calcium.
When using LEDs that have Nanometer specific diodes you must bring ambient temperatures up and/or lower the Rh% to open stomata more to increase transpiration.
An easy fix is to slowly lower your LED lights as the emitted light will raise relative temperatures. In my experience standard 70-75° isn't enough even for 5w diodes. My 135W Draw 5w diode LED panel is about 6" from the tops when winter hits and raising temps is a pain or simply improbable. Leaves like to sit at 80° LST and if your ambient temps are below that and your LED doesn't emit much heat you will have slowed transpiration. It can cause a plethora of problems and usually just ugly leaves.
If you have problems raising ambient temperatures switch to an HPS kit for 160$ on Amazon. Similar price to decent LED's.
Do not underestimate Leaf Surface Temperature as I believe but have not proven that it is the cause of "Leaf Tacos" and "Light Bleaching" not just that your "Lights are too close"
This is why some can get away with 600w hps 6" from the tops and others have issues passing a 16" barrier.
Plants loaded with silica will not droop the same nor will it taco in an attempt to slow transpiration as the cell walls have a phenomenal vigor to keep leaves in a photosynthesis promoting position.