Should new homes ever be built on public green spaces in cities?

I'd say building new homes on public green spaces should be avoided whenever possible. The main reason is that these spaces are essential for mental well-being and community life, especially in crowded cities like Shanghai. For example, near my apartment, there's a small park where people gather to exercise, chat, or just relax. It's a lifeline for many who live in high-rise buildings without much outdoor space. That said, I understand the pressure to accommodate growing populations, but preserving green areas should be a priority. A better solution might be to optimize existing urban spaces or build upwards rather than sacrificing parks and gardens.