Help with a diagnosis for my thai con please. I use my own soil mix in all my plants and a water meter so I dont think I’ve been overwatering. she gets regular fertilizer/ silica and I use timed grow lights to supplement during the winter and an infrared heater to keep the room temp stable. The windows are sealed with plastic over the winter so there isnt any drafts. My humidity stays around 80% . I preventatively treat all my new plants with spinosad and use bonide systemic granules in all my plants. I did forget to close the curtains but i dont think theres been enough sunlight to burn the plants (Im in Maryland). She has new leaf growth but out of no where these black spots are on three leaves. Im not sure what they could be or what I’m doing wrong here. If anyone might know, Id appreciate the help.