Attach Invoice plugin not compatible with Joomla 4

-- HikaShop version -- : 4.7.4
-- Joomla version -- : 4.3.2
-- Error-message(debug-mod must be tuned on) -- : error - Uncaught Throwable of type Error thrown with message "Call to undefined method Joomla\CMS\Application\SiteApplication::isAdmin()". Stack trace: #0 [ROOT]/libraries/src/Plugin/CMSPlugin.php(284): plgHikashopAttachinvoice->onAfterRender() #1 [ROOT]/libraries/vendor/joomla/event/src/Dispatcher.php(486): Joomla\CMS\Plugin\CMSPlugin->Joomla\CMS\Plugin\{closure}(Object(Joomla\Event\Event)) #2 [ROOT]/libraries/src/Application/EventAware.php(111): Joomla\Event\Dispatcher->dispatch('onAfterRender', Object(Joomla\Event\Event)) #3 [ROOT]/libraries/src/Application/CMSApplication.php(1031): Joomla\CMS\Application\WebApplication->triggerEvent('onAfterRender') #4 [ROOT]/libraries/src/Application/SiteApplication.php(724): Joomla\CMS\Application\CMSApplication->render() #5 [ROOT]/libraries/src/Application/CMSApplication.php(298): Joomla\CMS\Application\SiteApplication->render() #6 [ROOT]/includes/app.php(61): Joomla\CMS\Application\CMSApplication->execute() #7 [ROOT]/index.php(32): require_once('/home/customer/...') #8 {main}

error

We have recently updated to Joomla 4 however the "Attach PDF Invoice" plugin is not compatible with Joomla 4 giving the error above:

Can I get a Joomla 4 compatible plugin please.