fortunately the situation has been recovered! after giving up fertilizers and with the purchase of the humidifier they now look much healthier. some stigmas start to color
I think you are underwatering. And the pot size is 9l. I think you should give at least 1l of water or more. And before next feeding lift the pot and u can feel the weight so you know if the pot is dry. And maybe move down your lamp. Also make sure air conditioning is good. But this is just my opinion.
