Error 404 when sending WhatsApp template message with variable in Node.js

I'm trying to send a WhatsApp template message using the flow API as described in this guide. The template sends correctly when there's no variable in the body, but fails with a 404 error when I include a variable. Here's quote of my Node.js code:

let from = req.body.entry[0].changes[0].value.messages[0].from;

let flowtest= {
    messaging_product: "whatsapp",
    recipient_type: "individual",
    to: from,
    type: "template",
    template: {
        name: "flowtest",
        language: {
            code: "ar",
        },
        components: [
            {
                type: "body",
                parameters: [
                    {
                        type: "text",
                        text: from,
                    },
                ],
                type: "button",
                sub_type: "flow",
                index: "0",
            },
        ],
    },
};

I followed the official documentation and constructed the message payload as shown above. The request works without any errors when the message body does not contain any variables. However, adding a variable to the body component of the template (as shown in the code) causes the request to fail.

I expected the message to be sent successfully with the variable (from in this case) being included in the message body as specified.

When I try to send the message with the variable included in the body, I receive the following error:

Error sending message: Request failed with status code 404

Can anyone help me understand why this error occurs and how to fix it?

Variables for flow and template body are given separately. Try something like this

{
"messaging_product": "whatsapp",
"recipient_type": "individual",
"to": from,
"type": "template",
"template": {
    "name": "flowtest",
    "language": {
        "code": "ar"
    },
    "components": [
        {
            "type": "body",
            "parameters": [
                {
                    "type": "text",
                    "text": from
                }
            ]
        },
        {
            "type": "button",
            "sub_type": "flow",
            "index": "0",
            "parameters": [
                {
                    "type": "action",
                    "action": {
                        "flow_token": "FLOW_TOKEN",
                        "flow_action_data": initialData
                    }
                }
            ]
        }
    ]
}

}