Gas simulation issue when emptying an implicit account into a new implicit account

I am using the RPC helpers/scripts/run_operation to retrieve the consumed_gas associated with emptying an implicit account into a new (not allocated) implicit account. The returned consumed_gas value is 1420 units. However, when trying to pre-apply the operation using the RPC helpers/preapply/operations, and a gas_limit of 1420 (+buffer of 100), the status of the transaction is backtracked with proto.010-PtGRANAD.gas_exhausted.operation. It seems that the consumed_gas value returned by the run_operation is too low in this particular case. I need to call the pre-apply endpoint with a higher gas_limit to have it successful (i.e., 1920 gas units).

There are additional details/discussions on this thread: https://tezos-dev.slack.com/archives/C596FGNUR/p1631154106164100

Example response from the RPC helpers/scripts/run_operation:

{
      "contents": [
        {
          "kind": "transaction",
          "source": "tz3QJfCeRULYDZoTiD36de8qbsHsT9dQc9AP",
          "fee": "0",
          "counter": "490749",
          "gas_limit": "1040000",
          "storage_limit": "35996",
          "amount": "6999120",
          "destination": "tz3jTCGUobcz1GoYhU1QTsobRqmVytVDvYaE",
          "metadata": {
            "balance_updates": [],
            "operation_result": {
              "status": "applied",
              "balance_updates": [
                {
                  "kind": "contract",
                  "contract": "tz3QJfCeRULYDZoTiD36de8qbsHsT9dQc9AP",
                  "change": "-6999120",
                  "origin": "block"
                },
                {
                  "kind": "contract",
                  "contract": "tz3jTCGUobcz1GoYhU1QTsobRqmVytVDvYaE",
                  "change": "6999120",
                  "origin": "block"
                },
                {
                  "kind": "contract",
                  "contract": "tz3QJfCeRULYDZoTiD36de8qbsHsT9dQc9AP",
                  "change": "-64250",
                  "origin": "block"
                }
              ],
              "consumed_gas": "1420",
              "consumed_milligas": "1420000",
              "allocated_destination_contract": true
            }
          }
        }
      ],
      "signature": "edsigtkpiSSschcaCt9pUVrpNPf7TTcgvgDEDD6NCEHMy8NNQJCGnMfLZzYoQj74yLjo9wx6MPVV29CvVzgi7qEcEUok3k7AuMg"
    }

Example response from the RPC helpers/preapply/operations:

[
      {
        "contents": [
          {
            "kind": "transaction",
            "source": "tz3SpKcrMiiL1E8ijDmZwfbdcDxRxu2R73f2",
            "fee": "443",
            "counter": "498026",
            "gas_limit": "1520",
            "storage_limit": "257",
            "amount": "8934427",
            "destination": "tz3SHdNomLvR8bcdd3NossSjxWamPuG82UHL",
            "metadata": {
              "balance_updates": [
                {
                  "kind": "contract",
                  "contract": "tz3SpKcrMiiL1E8ijDmZwfbdcDxRxu2R73f2",
                  "change": "-443",
                  "origin": "block"
                },
                {
                  "kind": "freezer",
                  "category": "fees",
                  "delegate": "tz1Ke2h7sDdakHJQh8WX4Z372du1KChsksyU",
                  "cycle": 108,
                  "change": "443",
                  "origin": "block"
                }
              ],
              "operation_result": {
                "status": "backtracked",
                "errors": [
                  {
                    "kind": "temporary",
                    "id": "proto.010-PtGRANAD.contract.cannot_pay_storage_fee"
                  },
                  {
                    "kind": "temporary",
                    "id": "proto.010-PtGRANAD.gas_exhausted.operation"
                  }
                ],
                "balance_updates": [
                  {
                    "kind": "contract",
                    "contract": "tz3SpKcrMiiL1E8ijDmZwfbdcDxRxu2R73f2",
                    "change": "-8934427",
                    "origin": "block"
                  },
                  {
                    "kind": "contract",
                    "contract": "tz3SHdNomLvR8bcdd3NossSjxWamPuG82UHL",
                    "change": "8934427",
                    "origin": "block"
                  },
                  {
                    "kind": "contract",
                    "contract": "tz3SpKcrMiiL1E8ijDmZwfbdcDxRxu2R73f2",
                    "change": "-64250",
                    "origin": "block"
                  }
                ],
                "consumed_gas": "1420",
                "consumed_milligas": "1420000",
                "allocated_destination_contract": true
              }
            }
          }
        ],
        "signature": "p2sigQv2GeJHSzCXxxUasvAvTUsHzgxTCmYryLd6ihcXrtCuuzut6JNYVRR1iNTdgLG7DMVnp9Hv6LCgmmgqc316tC68tv5ynm"
      }
    ]