实体框架究竟以什么操作打开和关闭数据库连接?

So here is a link of the same question asked around 11 years ago. It's old and doesn't clear what I am looking for.

EF何时确切打开和关闭数据库连接?

Is it opened when we create a DbContext object or is it opened when we first make a request?

Is it closed when we hit SaveChanges() or is it closed when we either manually dispose the object or use it inside using() {}?

我浏览了Microsoft的在线资源,但找不到我想要的东西。

谢谢。