Hello,
We have a comments module on the homepage in a multilanguage website (4) on a php 7.2 server.
After the update the module gives a serious error. Before the k2 update to 2.9 there was no problem.
I think it has something to do with the helper.php file.

Here's the error i get:

Unknown column 'c.language' in 'where clause'
/var/www/vhosts/huisjeaandekust.nl/httpdocs/libraries/joomla/database/driver/mysqli.php:661

Call stack
# Function Location
1 () JROOT/libraries/joomla/database/driver/mysqli.php:661
2 JDatabaseDriverMysqli->execute() JROOT/libraries/joomla/database/driver.php:1691
3 JDatabaseDriver->loadObjectList() JROOT/modules/mod_k2_comments/helper.php:92
4 modK2CommentsHelper::getLatestComments() JROOT/modules/mod_k2_comments/mod_k2_comments.php:49
5 include() JROOT/plugins/system/t3/includes/joomla4/ModuleHelper.php:201
6 Joomla\CMS\Helper\ModuleHelper::renderModule()
7 call_user_func_array() JROOT/libraries/src/Cache/Controller/CallbackController.php:173
8 Joomla\CMS\Cache\Controller\CallbackController->get() JROOT/plugins/system/t3/includes/joomla4/ModuleHelper.php:629
9 Joomla\CMS\Helper\ModuleHelper::moduleCache() JROOT/libraries/src/Document/Renderer/Html/ModuleRenderer.php:95
10 Joomla\CMS\Document\Renderer\Html\ModuleRenderer->render() JROOT/libraries/src/Document/Renderer/Html/ModulesRenderer.php:47
11 Joomla\CMS\Document\Renderer\Html\ModulesRenderer->render() JROOT/libraries/src/Document/HtmlDocument.php:491
12 Joomla\CMS\Document\HtmlDocument->getBuffer() JROOT/libraries/src/Document/HtmlDocument.php:783
13 Joomla\CMS\Document\HtmlDocument->_renderTemplate() JROOT/libraries/src/Document/HtmlDocument.php:557
14 Joomla\CMS\Document\HtmlDocument->render() JROOT/libraries/src/Application/CMSApplication.php:1041
15 Joomla\CMS\Application\CMSApplication->render() JROOT/libraries/src/Application/SiteApplication.php:780
16 Joomla\CMS\Application\SiteApplication->render() JROOT/libraries/src/Application/CMSApplication.php:201
17 Joomla\CMS\Application\CMSApplication->execute() JROOT/index.php:49

could you take a look if this is perhaps a error in the commentsmodule on k2 2.9 in a multilanguage configuration?