After  k2 v2.11.20240911 update, pagination stop working again
edit view html php in line 594 components/com_k2/views/itemlist/
and works again 
Joomla 3.10.19 LTS (with Global Conf/ System / Legacy pagination behaviour YES)

 if ($document->getType() != 'json') {
            // Pagination
            jimport('');
            $total = (count($items)) ? $itemlistModel->getTotal() : 0;
            $pagination = new JPagination($total, $limitstart, $limit);
            $pagination->setAdditionalUrlParam('task', $task);
        }

After k2 v2.11.20241016 update pagination stop working again...
 view html php in line 594 components/com_k2/views/itemlist/

        if ($document->getType() != 'json') {
            // Pagination
            jimport('joomla.html.pagination');
            $total = (count($items)) ? $itemlistModel->getTotal() : 0;
            $pagination = new JPagination($total, $limitstart, $limit);
        }

With this change:
        if ($document->getType() != 'json') {
            // Pagination
            jimport('joomla.html.pagination');
            $total = (count($items)) ? $itemlistModel->getTotal() : 0;
            $pagination = new JPagination($total, $limitstart, $limit);
            $pagination->setAdditionalUrlParam('task', $task);
        }

Pagination works again BUT pagination on k2 TAG menus NOT working
Wrong url
site.url/tagmenu/itemlist/tag?start=10
Instead of Correct url
site.url/tagmenu?start=10
can someone help?
Joomla 3.10.19 lts

I remember you telling us how good Joomla 3 is compared to the bad 4 & 5. We have been forced to pay support for Joomla 3 LTS but after every update we are looking for solutions to get it working. on the contrary, for months now I have never encountered any problem with my other sites in joomla 5
 

solution from Joomla 3 LTS support:
components/com_k2/views/itemlist/
view html php  line 590

change from
        if ($document->getType() != 'json') {
            // Pagination
            jimport('joomla.html.pagination');
            $total = (count($items)) ? $itemlistModel->getTotal() : 0;
            $pagination = new JPagination($total, $limitstart, $limit);
      }

to 

        if ($document->getType() != 'json') {
            // Pagination
            jimport('joomla.html.pagination');
            $total = (count($items)) ? $itemlistModel->getTotal() : 0;
            $pagination = new JPagination($total, $limitstart, $limit);
            $pagination->setAdditionalUrlParam('task', $task);

            if ($task === 'tag') {
                $pagination->setAdditionalUrlParam('tag', JRequest::getString('tag'));
            }
      }