What is going on here? How do I stop this from affecting my other leaves?

There are these greyish crispy spots in the middle of some of my leaves. The rest of my Prayer plant seems fine for now but I don’t know what could have caused this. I’ve never seen this happen with any of my plants before. Please help. I don’t overwater it, I wait until the leaves starts to curl at the edges before I water it again and the pot drains well. I fertilize it when I start to see leaves turn yellow. This usually happens around the same time I see new growth and it tries to flower. I don’t let it flower by cutting them off as the flower stalks start to grow out to save the energy for the leaves. It sits under a solar lamp and has never shown signs of too littler or too much sun. Its humidity stays between 32% and 60% (right now it’s 51%) and its temperature is kept between 76.9 F (on rare days) and 66.9 F (also rare). Usually it stays between 68 and 74 in the room I keep it. Right now it’s 71 F. There are no signs of mold on the dirt and no signs of spider mites on the leaves or stalks. I’m really stumped as to what’s going on here. This is my favorite plant, I’ve had it for about 4 years now and nursed it to health from streatched stalks with tiny leaves to thick healthy stalks with leaves the size of my palm. I really don’t want to lose it. Please help. 🙏