Deep Copy vs Shallow Copy in Promise Resolution

What does this output?

let originalObject = { a: 1, b: { c: 2 } }
let shallowCopy = { ...originalObject }
let deepCopy = JSON.parse(JSON.stringify(originalObject))

Promise.resolve().then(() => {
  originalObject.b.c = 3
  console.log('Shallow Copy:', shallowCopy.b.c)
  console.log('Deep Copy:', deepCopy.b.c)
})

Correct Output

Shallow Copy: 3
Deep Copy: 2

Why this output?

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