Hello, about 10 months ago I received a Nepenthes Glandulifera × Talangensis. I set it on a west facing windowsill with a few hours of direct sunlight. Temps are around 80F to 85F (90+ on hot days) with night Temps being 60F to 75F. Humidity is around 50 percent during the day and 70 to 80 percent at night. It's been doing fine the last couple of months until March came along. During March I noticed one of it's leaves had a yellow spot. I didn't think to much of it as I thought it was sun damage. Eventually the spot developed a black center which spread across the leaf and killed it off. This was odd because it wasn't an old leaf. The next thing I know is that most of the plants leaves developed the same yellow spot and turned the leaves black so I cut most of them off fearing it would spread to the stem of the plant. After that I thought it was the end of it, I gave it some osmocote to give it a boost ( which was a bad idea and burned most of the leaf that retrieved the pellet) and then flushed the pot and set it aside. But I was wrong, it seems that it's happening again and I'm not sure what it is and what's causing it. I've asked many other forums and sub reddits and no one really knows what's the problem. Me and a few others think its caused by low humidity (I just bought a humidifier so hopefully that helps). Any thoughts on what this could be and how to fix it?