Adding file to column via v2 API gives 500 error

Hi All,
I am trying to upload an image file to column using add_file_to_column mutation.
Using the monday.com documentation I tried the postman example and it is working fine. But I am facing problems while uploading the picture by react native app. It is giving me Interval server error 500.
I just want to know if add_file_to_column supports base64 format because when I select an image on the mobile app, it returns base64 format and when I try with that. the response is 500.

Here’s my code:

const base64Data = insuranceImages[0].data // base64 Data
        const requestBody = {
            query: `
                mutation($file: File!) {
                add_file_to_column(
                    item_id: 4479452645,
                    column_id: "files",
                    file: $file,
                    ){
                    id
                    }
                }
            `,
            variables: {
                file: {
                    createReadStream : base64Data,
                    filename: insuranceImages[0].filename
                }
            }
        };

        fetch('https://api.monday.com/v2/file', {
            method: 'POST',
            body: JSON.stringify(requestBody),
            headers: {
                'Content-Type': 'multipart/form-data',
                "Authorization": CONFIG.MONDAY_API_KEY,
            },
            })
            .then((res) => {
                console.log('res',res);
                if (!res.ok) {
                console.warn('not ok');
                }})
            .catch((error) => {
                console.warn('error', error);
            });