A box grow

I find a number of new leaves develop. They all look healthy. However, her old leaves look light-green, which might result from nutrition deficiency or excess. As shown in the video, her leaves look stretched in the morning and withered in the evening. Her stems look a little bit thicker. Some part of them look turning red. I do not figure out why they are. The height of her body does not seem to change drastically through the week. I am afraid of her growth losing energy. I would like your suggestion to think on it, for we cannot grow without thinking. "Man is only a reed, the weakest in nature, but he is a thinking reed." In the city of New Leningrad, 2021-02-08.