Why flexbox keep vertical space between lines?

Question

Here is the layout:

<div
  style={{
    display: "flex",
    justifyContent: "space-between",
    width: "618px",
    flexWrap: "wrap",
  }}
>
  <input className={"input_3"} />
  <input className={"input_3"} />
  <input className={"input_3"} />
  <input className={"input_3"} />
</div>

Why the upper and lower lines are not closer to each other?

.input_3 {
  width: 272px;
  padding: 10px;
  height: 44px;
}