New growth with yellowing and curling down tips, t...

I think what has happened is an overdose of nutrients and /or overwatering has caused it to struggle absorbing micro nutes and minerals. Give her a good big flush and watch how much you're feeding her. Maybe reduce your feed by 1/2 and slowly increase over the next weeks. Also its the light a bit to far away, you can see the leaves are poking up to try and find the light, 😁🌱

It’s the oldest and lowest leaves that will signal the advance of a magnesium deficiency like for every mobiles nutrients deficiencies . In the beginning, bottom leaves will yellow and the tips will dry out into a crunchy brown. Your issue start on the bottom so it's not Mg def.

Doc green thumb is correct , it's magnesium deficiency you can tell from the yellowing at the tips of the seratzd edges and how it's spreading between the veins of the leafs. That's the symptom but the root cause is the intense light schedule, plants use more Mg for photosynthesis so it's pumping more than it can find. You can probably only do so much with extra Cal mag , and I know you don't want to hear this but you probably need to reduce the light schedule if you want to really fix the problem . The downward pointing tips is from root problems probably from slight overwatering over time. Just let the pot dry out more next time. You should try to break the problem roots down with any kind of chelation agent like enzymes , beneficial bacteria or humic and fluvic acid ... Hope this helps growmie ! 🚀

I would say over watering and possibly light burn depending on what distance is from top of plant .. she looks good besides that top inch of soil should be dry before you water again and now would be the time to think about adding some nutrients to her life cycle ..

Looks like it could be micro nutrient deficiency. I would also give a spray of epsom salt at 50 ppm in the morning under the leaves. How far away is the light from the top?