发现一个关于openssl_encrypt加密解密的问题，不知道是不是bug,哪位大神帮忙解答一下

//PHP Version 8.1.6
//Build Date May 11 2022 08:52:54
//Compiler Visual C++ 2019
//Thread API Windows Threads

class Crypt
{
    public $cipher_algo = "aes-128-ccm"; //加密方法
    public $passphrase = 'qw7%!^O'; //加密密钥
    public $options = 0; //数据格式选项（可选）
    public $iv = '-_)+^miwz]O#'; //加密初始化向量（可选）
    public $tag = '';

    public function encrypt($data): string
    {
        return openssl_encrypt($data, $this->cipher_algo, $this->passphrase, $this->options, $this->iv, $this->tag);
    }

    public function decrypt($data): string
    {
        return openssl_decrypt($data, $this->cipher_algo, $this->passphrase, $this->options, $this->iv, $this->tag);
    }
}
$crypt = new Crypt();

function encrypt(): string
{
    $crypt = new Crypt();
    $now = date("Y-m-d H:i:s");
    $encrypt = $crypt->encrypt(md5($now) . '@' . $now);
    return base64_encode($encrypt);
}

$token = encrypt();
$base64_decode = base64_decode($token);
$decrypt = $crypt->decrypt($base64_decode);

echo '第一次《br/》';
echo "token=" . $token . '《br/》';
echo "base64_decode=" . $base64_decode . '《br/》';
echo "decrypt=" . $decrypt . '《br/》';
echo '解密失败？《br/》《br/》《br/》';

$now = date("Y-m-d H:i:s");
$encrypt = $crypt->encrypt(md5($now) . '@' . $now);
$csrf = base64_encode($encrypt);

echo '第二次《br/》';
$token = $csrf;
$base64_decode = base64_decode($token);
$decrypt = $crypt->decrypt($base64_decode);

echo "token=" . $token . '《br/》';
echo "base64_decode=" . $base64_decode . '《br/》';
echo "decrypt=" . $decrypt . '《br/》';
echo '解密成功';

获得的结果长这个样子

第一次
token=dGk2d1o1WnNIcm5ZQ3RIWlJYWVRLY3QxeXloZk1mNThpOFZ4bzVnM2l3V3F5blJhcGtnTkk3OWY0cHkxMzdsQ1UwWDdoQT09
base64_decode=ti6wZ5ZsHrnYCtHZRXYTKct1yyhfMf58i8Vxo5g3iwWqynRapkgNI79f4py137lCU0X7hA==
decrypt=
解密失败？


第二次
token=dGk2d1o1WnNIcm5ZQ3RIWlJYWVRLY3QxeXloZk1mNThpOFZ4bzVnM2l3V3F5blJhcGtnTkk3OWY0cHkxMzdsQ1UwWDdoQT09
base64_decode=ti6wZ5ZsHrnYCtHZRXYTKct1yyhfMf58i8Vxo5g3iwWqynRapkgNI79f4py137lCU0X7hA==
decrypt=57869668d9ac3ec22eda6afd9447069f@2023-07-16 09:12:54
解密成功

第一次加密解密与第二次的区别是，第一次使用函数返回加密内容，而第二次直接把加密过程代码写在过程里，有哪位大神能看出问题吗？虚心请教一下原因。谢谢！

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