Welcome to the Jungle !!
Have fun here.
It is very normal for the plant to decline once it leaves the store or green house and goes into your home, leaves turn brown, yellow and the plant just looks horrible. And it just takes a few weeks to rear its ugly face.
Cut way back on water because the first thing a person does is start watering the plant once it looks bad and that leads to more problems including death to your plant. I also suspect that the windows in your high-rise are energy efficient and Low E so they might not be getting as much light as you hoped they would.
Here is a photo of leaves that come off my plants on a weekly basis; for me this is expected.
However I can see your concern with your new plant.
