I recently bought this plant from someone. The leaf edges were curled and it seemed like the plant was dehydrated. However, I checked the soil and it was moist in the middle, so it definitely got watered a few days ago. I leave my plant near a southwest-facing window for sufficient sun. Also keep my windows closed for the night to protect it from the cold when it drops down to 44F. It does get to 60F in the afternoon though, but the sun makes things warm. Not sure what the issue is here.
I also took a closer look at the leaves. One smaller leaf appears green but has a yellow underside (1st, 6th photo). Another leaf had some "bubbly" scars along the leaf midrib (2nd, 3rd photo, overwatering?). They look too "scar-like" to be actual bugs. Another leaf has turned gray/brown in the middle, almost as if it was drying out (5th, 7th, 8th photo). Humidity issues? The leaves are either drooping or curling inwards (last photo, 4th photo).
I also checked under the leaves, and they all had some white powdery dust alongside their midribs (1st, 6th photo). I can't figure out if it's just some weird dust or an actual pest. They feel very, very powdery to the touch, and I don't see any big chunks. Unless these pests are supposed to be tiny.
Hope this situation is salvageable. Thank you so much!