Some type of nutrient deficiency or burn? Not all ...

It’s the beginning of the senescence. It’s natural, it’s part of plant life cycle.

Since the leaves are drooping / clawwing downwards, I think not only you've got some lightburn as the other posters mentioned, I think medium is watterlogged, and can't uptake nutrients as such. Let the soil dry until top inch is dry and under that slightly moist until refeeding. After setting lights slightly further or train buds downwards from the light if not possibe, slightly feed he leaves with a spray of calmag. Easy with the other nutes in this stage. It could still be a nitrogen excess. As final option I name Sulphur deficiency, its rare but I recently gad this but easy to check: do you have purple lines on your main stem? If so, just feed leaves with a solution: half liter of water + one teaspoon of epsom salt plus a little flowerfeed (High in P and K). When doing this, set ventilation higher, I keep my growspace open until leaves are dry and prevent hitting the buds. Good luck and happy smoking !

I'd do a round of FloraKleen next nutrient swap. I suspect alkaline salt buildup.

Hi, it can be a few things. Cal mag deficiency, light too close, heat, or a combo of all three! LEDs eat up the mag in the plants so this can cause the yellowing. Try raising the light a touch. Good luck! ✌️🏻💚🌿💨