My opinion would be:
-High temps and Low RH, most likely caused by the lights, would also cause some nute burn at the tips from heavy transpiration.
-Curved leaf tips at the top but not the bottom also confirm High Heat and Low RH since the moist soil should in theory help the lower parts of the plant.
-The Cal mag spotting could just be an off balance caused by the plant working more up top and bailing on the bottom leaves that are worthless to it.
-If you do add some Cal Mag to solve the bronze and yellow spots, lower the rest of the feed a little. That leaf is more than dark enough "as is" considering the circumstances and even too much N, P or K at this point can affect smoke. Less is more (or at least better) later on.
Few questions:
- Are these in a Pro-Mix/Perlite Mix or soil based? PH could be an issue but that depends on whats there to be accurate.....
-What kind of nutes do we have going through and how much?
-What growing environment? Temp? RH? Size? Exhaust or no?
That should be enough to start lol high and rambling so ignore if you want