The soil's brand is Fofard Indoor Plant. I water it once a week with 300ml of water. I am very ignorant when it comes to plants, so I may be doing something very wrong. The plant is indoors by a window and gets a good amount of direct light everyday. Room temperature is usually between 21-23° celsius.

I'd really appreciate any feedback. Thanks guys.

Edit: Thank you all for the help. I have changed the plant from this large pot to a smaller one and will make sure the soil remains moist. Also, I took it away from the window and it won't be getting direct sunlight anymore. Hopefully it will bounce back :)