Hey there! 😊
From the looks of it, those brown tips are likely caused by a mild nutrient burn. Your feeding schedule looks pretty active, and it’s easy to slightly overdo it—especially during the early stages of flowering when the plants are still adjusting.
It could also be a bit of light stress if your LEDs are running close and strong. If the damage is mostly on the top leaves nearest the light, raising the fixture a little or dimming slightly could help.
To correct it, I’d suggest giving a light flush with pH-balanced water (around 6.3–6.5), and ease up just a bit on the next few feedings. Check how the new growth looks—if it’s healthy and green, you're back on track!
You're doing great—small issues like this are totally normal. Happy growing and good luck with the rest of the run! 🌱✨