Creating system tags on Drupal 9 results in a fatal error because of missing config_export.

When creating a new System tag entity on Drupal 9, this results in the following error:

Drupal\Core\Config\Schema\SchemaIncompleteException: Entity type 'Drupal\Core\Config\Entity\ConfigEntityType' is missing 'config_export' definition in its annotation in Drupal\Core\Config\Entity\ConfigEntityBase->toArray() (line 251 of core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php).
Drupal\Core\Config\Entity\ConfigEntityStorage->mapToStorageRecord() (Line: 283)
Drupal\Core\Config\Entity\ConfigEntityStorage->doSave() (Line: 452)
Drupal\Core\Entity\EntityStorageBase->save() (Line: 263)
Drupal\Core\Config\Entity\ConfigEntityStorage->save() (Line: 339)
Drupal\Core\Entity\EntityBase->save() (Line: 591)
Drupal\Core\Config\Entity\ConfigEntityBase->save() (Line: 47)
Drupal\system_tags\Form\SystemTagForm->save()
call_user_func_array() (Line: 113)
Drupal\Core\Form\FormSubmitter->executeSubmitHandlers() (Line: 51)
Drupal\Core\Form\FormSubmitter->doSubmitForm() (Line: 593)
Drupal\Core\Form\FormBuilder->processForm() (Line: 321)
Drupal\Core\Form\FormBuilder->buildForm() (Line: 73)
Drupal\Core\Controller\FormController->getContentResult()
call_user_func_array() (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 573)
Drupal\Core\Render\Renderer->executeInRenderContext() (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext() (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 158)
Symfony\Component\HttpKernel\HttpKernel->handleRaw() (Line: 80)
Symfony\Component\HttpKernel\HttpKernel->handle() (Line: 57)
Drupal\Core\StackMiddleware\Session->handle() (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle->handle() (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle() (Line: 52)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle() (Line: 23)
Stack\StackedHttpKernel->handle() (Line: 705)
Drupal\Core\DrupalKernel->handle() (Line: 19)