UnblockUser.php

<?php

namespace Drupal\user\Plugin\Action;

use Drupal\Core\Action\ActionBase;
use Drupal\Core\Action\Attribute\Action;
use Drupal\Core\Session\AccountInterface;
use Drupal\Core\StringTranslation\TranslatableMarkup;

/**
 * Unblocks a user.
 */
class UnblockUser extends ActionBase {
  
  /**
   * {@inheritdoc}
   */
  public function execute($account = NULL) {
    // Skip unblocking user if they are already unblocked.
    if ($account !== FALSE && $account->isBlocked()) {
      $account->activate();
      $account->save();
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public function access($object, ?AccountInterface $account = NULL, $return_as_object = FALSE) {
    /** @var \Drupal\user\UserInterface $object */
    $access = $object->status
      ->access('edit', $account, TRUE)
      ->andIf($object->access('update', $account, TRUE));
    return $return_as_object ? $access : $access->isAllowed();
  }

}