I am trying to pass a json object as string through power apps to power automate. The json has an attachment that the flow will mail. The flow runs successfully, however the attached file won't open.

ChangeOfBankingDetails.Run(
JSON(
    {
        acc_holder: txtAccountHolder.Text,
        acc_number: txtAccountNumber.Text,
        acc_type: cmbAccountType.Selected.Value,
        bank_name: cmbBankName.Selected.Value,
        brn_code: txtBankBranchCode.Text,
        brn_name: txtBankBranchName.Text,
        proof_of_account: {
            Name: First(attPOA.Attachments).Name,
            ContentBytes: First(attPOA.Attachments).Value
        }
    }
)

)