Would love to get some insight on whether this is ...

I would definitely increase the nutrient levels and see if that makes a difference. Make sure you're checking your pH and leaving soil to dry nicely before watering. Maybe move the light a bit lower? But I see it as nutrient defiency, if they can't get the nutrients from the soil, they will suck it from the plant as needed, and this is why you'll have lighter green leaves or discolouration.

One thing I don’t like that’s not shared on GD is the type and intensity of the lighting system until after you complete the project. I have noticed with today’s high end LED lights the intensity creates a higher need for cal mag. I had several plants go through a very similar issue over the course of 6 months until I realized that the need for phosphorus when you switch lighting schedules is nearly double that of a feeding chart on ANY manufacturers bottle or chart. It’s very uncommon to see a toxicity in cal-mag and phosphorus so I’d suggest doing a quick internet search and if you agree raising your levels. Hope it helps!

I haven't updated my nutrient levels in a while but ya your levels of nutes seem on the lower end of things .. that one leaf look chewed on for sure but pest can hide pretty good sometimes .The girls seem to be needing more cal mag for sure it is an essential additive to anyone garden and growing in coco/perlite means you have even more control on how they will grow and drink .you said you were gonna try it higher and if all else fails flush your on the right path .cheers..

Your nutrient levels seem on the low end of the spectrum to me... even my least hungry strains are drinking over triple that