我创建了一个函数来解密，但是在解密的时候一些字符被破坏了。这个问题可能是什么引起的？
{“text”：“aynīsī "}
1999年12月15日，纽约
{“text”：“aynìs "}

const encryptionType = 'aes-256-cbc';
const encryptionEncoding = 'base64';
const encryptionEncodingHex = 'hex';
const bufferEncryption = 'utf-8';

const decryptJwt = (cipherText) => {
  const buff = Buffer.from(cipherText, encryptionEncoding);
  const KEY = Buffer.from(SECRET, bufferEncryption);
  const IV = Buffer.alloc(16);

  const decipher = crypto.createDecipheriv(encryptionType, KEY, IV);
  const deciphered = decipher.update(buff).toString(bufferEncryption) + decipher.final().toString(bufferEncryption);

  return deciphered;
};