Changing the element by index 2D array in JavaScript

Question

I am going to change the element of 2D array by its indices

When I was solving CodeWars problems. I tried to change the element which located 4th row 2nd column, the compiler changed all the elements located in the 2nd column

function score( dice ) {
  // Fill me in!
  const map = new Map();
  let arr = [];
  let init = [0, 0, 0, 0, 0, 0, 0];
  for(let i=0; i<6; i++) {
    arr.push(init);
  }
  
  arr[3][1] = 1000;
  
  console.log(arr);
}

/**
CONSOLE
[
  [
    0, 1000, 0, 0,
    0,    0, 0
  ],
  [
    0, 1000, 0, 0,
    0,    0, 0
  ],
  [
    0, 1000, 0, 0,
    0,    0, 0
  ],
  [
    0, 1000, 0, 0,
    0,    0, 0
  ],
  [
    0, 1000, 0, 0,
    0,    0, 0
  ],
  [
    0, 1000, 0, 0,
    0,    0, 0
  ]
]
*/

Is the problem with my code or with the compiler?