Hi
@Yung_Ar9! Your plant is having a Calcium deficiency, you need to react quickly or it will spread accross the whole plant. This could be related to a wrong pH range, so double-check your pH-pen and make sure it's perfectly calibrated. Growing in soil, calcium is best absorbed by the roots in the 6.2 – 7.0 pH range, I see your pH is 6.0 so that could be a clue. If you want a quick fix, add some Calcium supplement into your next feedings (Epsom salt works well). Hope this will help, let me know in the comments section if you need any further information, and happy growing! 👊