Error uninstalling the module

I had the same issue, where publish_state and unpublish_state were missing and the status report showed "Mismatched entity and/or field definitions".

I wrote this controller to fix it.

<?php

namespace Drupal\my_module\Controller;

use Drupal\Core\Controller\ControllerBase;
use Symfony\Component\DependencyInjection\ContainerInterface;

/**
 * Returns responses for my_module routes.
 */
class MyModuleController extends ControllerBase {

  /**
   * The entity definition update manager.
   *
   * @var \Drupal\Core\Entity\EntityDefinitionUpdateManagerInterface
   */
  protected $entityDefinitionUpdateManager;

  /**
   * The entity last installed schema repository.
   *
   * @var \Drupal\Core\Entity\EntityLastInstalledSchemaRepositoryInterface
   */
  protected $entityLastInstalledSchemaRepository;

  /**
   * The module handler.
   *
   * @var \Drupal\Core\Extension\ModuleHandlerInterface
   */
  protected $moduleHandler;

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    $instance = parent::create($container);
    $instance->entityDefinitionUpdateManager = $container->get('entity.definition_update_manager');
    $instance->entityLastInstalledSchemaRepository = $container->get('entity.last_installed_schema.repository');
    $instance->moduleHandler = $container->get('module_handler');
    return $instance;
  }

  /**
   * Fix schema after installing scheduler_content_moderation_integration.
   *
   * After enabling the module via config sync the publish_state and
   * unpublish_state fields were missing with no way to restore them and no way
   * to uninstall the module. This function installs the missing fields to allow
   * the module to be uninstalled.
   */
  public function fixSchedulerContentModerationIntegration() {
    $updated = FALSE;
    if ($this->moduleHandler->moduleExists('scheduler_content_moderation_integration')) {
      $entity_type = $this->entityDefinitionUpdateManager->getEntityType('node');
      $installed = $this->entityLastInstalledSchemaRepository->getLastInstalledFieldStorageDefinitions($entity_type->id());
      $definitions = scheduler_content_moderation_integration_entity_base_field_info($entity_type);
      foreach ($definitions as $field_name => $definition) {
        if (empty($installed[$field_name])) {
          $this->entityDefinitionUpdateManager->installFieldStorageDefinition($field_name, $entity_type->id(), 'scheduler_content_workbench_moderation_integration', $definition);
          $this->messenger()->addMessage($this->t('Field %field_name installed.', [
            '%field_name' => $field_name,
          ]));
          $updated = TRUE;
        }
      }
    }
    if (!$updated) {
      $this->messenger()->addMessage($this->t('No schema updates required.'));
    }
    return $this->redirect('system.status');
  }

}

#6 worked for me very well.

In case someone doesn't know how to implement above's code, you can create an specific url path to run that code in your routing.yml file:

my_module.fix_scheduler_module:
  path: /admin/config/user-interface/fix-scheduler-module
  defaults:
    _title: 'Fix Scheduler module'
    _controller: '\Drupal\my_module_folder\Controller\MyModuleController::fixSchedulerContentModerationIntegration'
  requirements:
    _access: 'TRUE'

Here you can have a hook_update solution as well
https://www.drupal.org/project/scheduler_content_moderation_integration/...