Magento 2 – checkout_submit_all_after event is not working after checkout completion

I have need to get Order information in checkout_submit_all_after event observer in Afterpay Payment Method Module. I am trying to add this event in that module.

File Path: app/code/Afterpay/Afterpay/etc/events.xml

< ?xml version="1.0"?>


    
        
    

File Path: app/code/Afterpay/Afterpay/Observer/SaveOrderAfterSubmitObserver.php

< ?php
/**
 * Magento 2 extensions for Afterpay Payment
 */
namespace AfterpayAfterpayObserver;

use MagentoFrameworkEventObserverInterface;
use MagentoSalesModelOrder;

class SaveOrderAfterSubmitObserver implements ObserverInterface
{
    /**
     *
     * @var MagentoFrameworkRegistry
     */
    protected $coreRegistry;

    /**
     * @param MagentoFrameworkRegistry $coreRegistry
     */
    public function __construct(
        MagentoFrameworkRegistry $coreRegistry
    ) {
        $this->coreRegistry = $coreRegistry;
    }

    /**
     * Save order into registry to use it in the overloaded controller.
     *
     * @param MagentoFrameworkEventObserver $observer
     * @return $this
     */
    public function execute(MagentoFrameworkEventObserver $observer)
    {
        /* @var $order Order */
        $order = $observer->getEvent()->getData('order');
        $orderId = $order->getId();
        print_r($orderId); die('1');
        $writer = new ZendLogWriterStream(BP . '/var/log/testingObserver.log');

        $logger = new ZendLogLogger();

        $logger->addWriter($writer);

        $logger->info($orderId."OrderId");

    }
}

I only want to use this event. I have checked several other questions where this event is not working but all the answers are asking to use different event. But I don’t want to use any other event. Please help me to get work this event in Magento 2.