Hey bud, I’m going to assume you’re ph is correct. If so, you almost certainly have a calcium or magnesium deficiency. It looks more to me like calcium as I went through the same issue on an amnesia haze grow and the pics of it online are identical to mine/yours. Question - did you “pre-prime” your medium with cal mag before planting? I see you’re already using a cal mag supplement and if so, then I’d agree you could be faced with some nute lockout as well. That said, if you’re only seeing this on 1 or 2 leaves it may not be all that much of an issue and easily corrected with some moderation. I’d give them a solid ph’d water “rinse” (not a flush) with 30% runoff. Then some cal mag after dry and slowly dial back up the nutes over time. This is could be considered a low stress way to identify your issue. Maybe even leave out the nutes until flower starts. You’ve only got a couple weeks until then anyway. Hope it helps - you’ve got some great opinion here already👍