Magento 2 Unable to update customer data during passing to customer login observer

In magento 2 I am trying to update session_cutoff column in table customer_entity during login

Below is my code which I add in observer using event customer_login

public function execute(MagentoFrameworkEventObserver $observer)
    {
        $this->_customerSession->setGTMSuccessfulLogin($this->helper->successfulLoginPushData());

        $customer_data = $observer->getEvent()->getCustomer();
        $gtrustCustNo = $customer_data->getData('gtrust_custno');

        $param = array('custNo' => $gtrustCustNo);
        $result = $this->_gtrustApiHelper->getUserBenefit(($param));
        $customer = $this->customerFactory->create();
        $customer = $customer->setWebsiteId(1);
        // set sessionCutOff to null
        $customer = $customer->setSessionCutOff(NULL);
        $customer = $customer->loadByEmail($customer_data->getEmail());
        $customerData = $customer->getDataModel();       
        if (isset($result['resultData']['result']['usableSaveamt'])){
            $saveamt = $result['resultData']['result']['usableSaveamt'];
            $this->_customerSession->setCustomerPoint($saveamt);
            $customerData->setCustomAttribute('customer_point', $saveamt);
        }
        if (isset($result['resultData']['result']['usePbDeposit'])){
            $deposit = $result['resultData']['result']['usePbDeposit'];
            $customerData->setCustomAttribute('customer_deposit', $deposit);
        }
        if (isset($result['resultData']['result']['usableCouponCnt'])){
            $coupon = $result['resultData']['result']['usableCouponCnt'];
            $this->_customerSession->setCouponDownloaded($coupon);
            $customerData->setCustomAttribute('coupon_downloaded', $coupon);
        }        
        $customer->updateData($customerData);
        $customer->save();        
    }

As you can see I already added the $customer->setSessionCutOff(NULL); to set the customer session_cutoff to null but apparently when I try login the value doesnt change

I already var_dump to confirm whether the observer is being read or not, and able to see clearly that the soure code is being read and passed through during login

$customer->setWebsiteId(1) also didn’t work I check, I already dicompile, upgrade and cache clean but nothing works

Please help check and advice on what is causing this issue