create for every array in array elemet an extra object strange behavior

Question

Why the first example does not give me the expected result, but the second. They are basically the same. My expected console output of processedData2 should be

[
  {
    "id": "someid",
    "parts": [
      {
        "part_id": "1"
      }
    ]
  },
  {
    "id": "someid",
    "parts": [
      {
        "part_id": "2"
      }
    ]
  },
  {
    "id": "someid",
    "parts": [
      {
        "part_id": "3"
      }
    ]
  }
]

like in the second example.

Example 1 (should work since "processedData" is the same as in the second example, but doesn't)

let putData = [
  {
    id: 'someid',
    parts: [
      {
        part_id: '1',
      },
      {
        part_id: '2',
      },
      {
        part_id: '3',
      },
    ],
  },
];
let processedData = [];
for (let i of putData) {
  for (let o in i.parts) {
    processedData.push(i);
  }
}
console.log('processed Data ', processedData);
let processedData2 = processedData;
console.log('processedData 2 before ', processedData2);
for (let i = 0; i < processedData.length; i++) {
  console.log(processedData[i].parts[i]);
  processedData2[i].parts = [processedData[i].parts[i]];
  console.log(processedData2[i].parts[i]);
}
console.log('processedData 2 after', processedData2);

Second Example (works correct)

let processedData = [
  {
    id: 'someid',
    parts: [
      {
        part_id: '1',
      },
      {
        part_id: '2',
      },
      {
        part_id: '3',
      },
    ],
  },
  {
    id: 'someid',

    parts: [
      {
        part_id: '1',
      },
      {
        part_id: '2',
      },
      {
        part_id: '3',
      },
    ],
  },
  {
    id: 'someid',
    parts: [
      {
        part_id: '1',
      },
      {
        part_id: '2',
      },
      {
        part_id: '3',
      },
    ],
  },
];
console.log('processed Data ', processedData);
let processedData2 = processedData;
console.log('processedData 2 before ', processedData2);
for (let i = 0; i < processedData.length; i++) {
  console.log(processedData[i].parts[i]);
  processedData2[i].parts = [processedData[i].parts[i]];
  console.log(processedData2[i].parts[i]);
}
console.log('processedData 2 after', processedData2);

heres a link to a demo in Stackblitz: https://stackblitz.com/edit/js-8iqqp7?file=index.js