[v5] Some confusion about "immutable updates" for react-query

[yegao]

I have done a demo here https://codesandbox.io/s/hopeful-hertz-ocvp6e
Here's what really confused me:

// 1. not working
dataset.k = "B";
dataset = { ...dataset };
queryClient.refetchQueries({ queryKey: ["dataset"] });

// 2. working
dataset = { ...dataset, k: "B" };
queryClient.refetchQueries({ queryKey: ["dataset"] });

so what difference between

dataset.k = "B";
dataset = { ...dataset };

and

dataset = { ...dataset, k: "B" };

I don't know that they are any different, they all produce different object references than before。
But it does produce different results. Does react-query do anything special?