在此行中：

$base = 'GET' . "&" . urlencode('https://7085372.suitetalk.api.netsuite.com/services/rest/record/v1/customer/') . "&" . urlencode("oauth_consumer_key=" . urlencode($consumer_key) . "&oauth_nonce=" . urlencode($oauth_none) . "&oauth_signature_method=" . urlencode($oauth_signature_method) . "&oauth_timestamp=" . urlencode($timeStamp) . "&oauth_token=" . urlencode($oauth_token) . "&oauth_version=" . urlencode($oauth_version) . "&realm=" . urlencode($realm));

从urlencode("oauth_consumer_key=" .到"&realm=" . urlencode($realm));，您使用了两次url_encoding，并且您使用了两次url_encoding =符号。因此，您的$authorization字符串绝对是错误的，并且它会导致参数丢失。
当你写这么长的一行时，很难看清。最好是这样写：

$base = 'GET&' . urlencode('https://7085372.suitetalk.api.netsuite.com/services/rest/record/v1/customer/')
    . '&oauth_consumer_key=' . urlencode($consumer_key)
    . '&oauth_nonce=' . urlencode($oauth_none)
    . '&oauth_signature_method=' . urlencode($oauth_signature_method)
    . '&oauth_timestamp=' . urlencode($timeStamp)
    . '&oauth_token=' . urlencode($oauth_token)
    . '&oauth_version=' . urlencode($oauth_version)
    . '&realm=' . urlencode($realm);

但是，使用数组和http_build_query()函数会更好，方法如下：

$url = 'https://7085372.suitetalk.api.netsuite.com/services/rest/record/v1/customer/';

$data = array(
    'oauth_consumer_key' => $consumer_key,
    'oauth_nonce' => $oauth_none,
    'oauth_signature_method' => $oauth_signature_method,
    'oauth_timestamp' => $timeStamp,
    'oauth_token' => $oauth_token,
    'oauth_version' => $oauth_version,
    'realm' => $realm,
);

$base = 'GET&' . urlencode($url) . '&' . http_build_query($data);

注意.-另外，最好为url使用一个变量，因为您要多次使用它。

但是，也许还有更多的问题。我不知道你是否做得很好的要求。
最好有一个生成OAuth签名的函数。

以下是您的代码的重新制作：

$url = 'https://7085372.suitetalk.api.netsuite.com/services/rest/record/v1/customer/';
$consumer_secret = 'xxxxxxxxxx';
$token_secret = 'xxxxxxxxxx';
$data = array(
    'oauth_consumer_key' => 'xxxxxxxxxx',
    'oauth_nonce' => Str::random(11),
    'oauth_signature_method' => 'HMAC-SHA256',
    'oauth_timestamp' => Carbon::now()->timestamp,
    'oauth_token' => 'xxxxxxxxxx',
    'oauth_version' => '1.0',
    'realm' => 'xxxxxxxxxx',
);

$oauth_signature = generateOauthSignature(
    'GET',
    $url,
    $data['oauth_consumer_key'],
    $data['oauth_nonce'],
    $data['oauth_signature_method'],
    $data['oauth_timestamp'],
    $data['outh_version'],
    $consumer_secret,
    $token_secret,
    $data['oauth_token'],
    array('realm' => $data['realm']),
);
$authorization = 'OAuth ';
foreach ($data as $key => $val) {
    $authorization .= ',' . $key . '=' . $val;
}
$authorization .= ',oauth_signature=' . $oauth_signature;

try {
    $client = new Client();
    $headers = [
        'Authorization' => $authorization,
        'Content-Type' => 'application/json',
        'Cookie' => 'NS_ROUTING_VERSION=LAGGING'
    ];
    $body = '';

    $request = new Request('GET', $url, $headers, $body);
    $res = $client->sendAsync($request)->wait();
    dd('here', $res, $res->getBody());
} catch (RequestException $e) {
    dd($e->getResponse(), $e);
}

function generateOauthSignature($method, $url, $consumerKey, $nonce, $signatureMethod, $timestamp, $version, $consumerSecret, $tokenSecret, $tokenValue, $extraParams = array())
{
    $base = strtoupper($method) . "&" . rawurlencode($url) . "&"
        . rawurlencode("oauth_consumer_key=" . $consumerKey
        . "&oauth_nonce=" . $nonce
        . "&oauth_signature_method=" . $signatureMethod
        . "&oauth_timestamp=" . $timestamp
        . "&oauth_token=" . $tokenValue
        . "&oauth_version=" . $version);

        if (!empty($extraParams)) {
            $base .= rawurlencode("&" . http_build_query($extraParams));
        }

    $key = rawurlencode($consumerSecret) . '&' . rawurlencode($tokenSecret);
    $signature = base64_encode(hash_hmac('sha1', $base, $key, true));

    return rawurlencode($signature);
}