Can't save pages anymore

Problem/Motivation

When a user saves a page they now receive this error

The website encountered an unexpected error. Please try again later.
TypeError: Illegal offset type in Drupal\Core\Entity\ContentEntityStorageBase->loadRevision() (line 639 of core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php).
Drupal\Core\Entity\ContentEntityStorageBase->loadRevision(Object) (Line: 59)
Drupal\content_moderation_notifications\NotificationInformation->getPreviousState(Object) (Line: 86)
Drupal\content_moderation_notifications\NotificationInformation->getTransition(Object) (Line: 107)
Drupal\content_moderation_notifications\NotificationInformation->getNotifications(Object) (Line: 90)
Drupal\content_moderation_notifications\Notification->processEntity(Object) (Line: 29)
content_moderation_notifications_entity_update(Object)
call_user_func_array('content_moderation_notifications_entity_update', Array) (Line: 403)
Drupal\Core\Extension\ModuleHandler->invokeAll('entity_update', Array) (Line: 251)
Drupal\Core\Entity\EntityStorageBase->invokeHook('update', Object) (Line: 897)
Drupal\Core\Entity\ContentEntityStorageBase->invokeHook('update', Object) (Line: 602)
Drupal\Core\Entity\EntityStorageBase->doPostSave(Object, 1) (Line: 782)
Drupal\Core\Entity\ContentEntityStorageBase->doPostSave(Object, 1) (Line: 527)
Drupal\Core\Entity\EntityStorageBase->save(Object) (Line: 802)
Drupal\Core\Entity\Sql\SqlContentEntityStorage->save(Object) (Line: 339)
Drupal\Core\Entity\EntityBase->save() (Line: 270)
Drupal\node\NodeForm->save(Array, Object)
call_user_func_array(Array, Array) (Line: 114)
Drupal\Core\Form\FormSubmitter->executeSubmitHandlers(Array, Object) (Line: 52)
Drupal\Core\Form\FormSubmitter->doSubmitForm(Array, Object) (Line: 592)
Drupal\Core\Form\FormBuilder->processForm('node_article_edit_form', Array, Object) (Line: 144)
Drupal\autosave_form\Form\AutosaveFormBuilder->processForm('node_article_edit_form', Array, Object) (Line: 320)
Drupal\Core\Form\FormBuilder->buildForm(Object, Object) (Line: 97)
Drupal\autosave_form\Form\AutosaveFormBuilder->buildForm(Object, Object) (Line: 73)
Drupal\Core\Controller\FormController->getContentResult(Object, Object) (Line: 39)
Drupal\layout_builder\Controller\LayoutBuilderHtmlEntityFormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 564)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 158)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 80)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 42)
Drupal\force_password_change\Service\ForcePasswordChangeRedirectMiddleware->handle(Object, 1, 1) (Line: 58)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 708)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)