是你打印截断了，而不是返回不完整

public function profit_sharing($transaction_id,$out_trade_no,$account,$total_fee){
    $resp = $this->instance
        ->chain('v3/profitsharing/orders')
        ->post(['json' => [
            'sub_mchid' => $this->config['sp_mchid'],//子商户号
            'appid' => $this->config['wx_small_appid'],//应用ID
            'sub_appid' => $this->config['wx_sub_appid'],//子商户应用ID
            'transaction_id' => $transaction_id,
            'out_order_no' => $out_trade_no,
            'unfreeze_unsplit' => true,
            'receivers' => [
                'type'=>'MERCHANT_ID',//分账接收方类型,
                'account'=>$account,//分账接收方账号
                'amount'=>$total_fee,
                'description'=>'分账商户'
            ]
        ]]);
    return $resp->getBody();

}