_.cloneDeep({ prop: { subprop: 'value' } })

const trueclone = (obj) => {

    const cloned = Array.isArray(obj) ? [] : {}

    const keys = Object.keys(obj)

    const values = Object.values(obj)

    const length = keys.length

    for (let i = 0; i < length; i++) {

        if (typeof values[i] === 'object') values[i] = trueclone(values[i])

        cloned[keys[i]] = values[i]

    }

    return cloned

}

​

trueclone({ prop: { subprop: 'value' } })

structuredClone({ prop: { subprop: 'value' } })