Saving Attachments as Base64 from Graph Explorer

Question

I have a Node.js application that picks emails from Graph Explorer and saves them to an MS SQL Server database. I have an issue with my attachments though. I am trying to save the contentBytes as they are from 'Graph Explorer' but when I do this, it is truncated. The data type is of type varbinary(max). So, I switched to an alternative to save as Binary data, but this seems to be malformed as I can't convert it back to pdf. My main aim here is to save PDFs only.

Below is the snippet:

for (const attachment of attachmentData) {
  if (attachment.contentType === 'application/pdf' && attachment.contentBytes) {
         // Convert attachment.contentBytes to binary buffer
            const contentBuffer = Buffer.from(attachment.contentBytes, 'base64');
data type conversion
                        const attachmentInsertResult = await transaction.request().query`
                            INSERT INTO Attachments (email_id, contentBytes)
                            OUTPUT INSERTED.id
                            VALUES (${emailId}, ${contentBuffer});
                        `;
                        attachmentIds.push(attachmentInsertResult.recordset[0].id);
                    }
                }