OK, so I have done a little experimenting. I've amended the 2.4.3 toolbar.phtml code to include the missing 2 elements in the else statement (seemed like a logical thing to have included, just in case the bottom block is missing in the theme - kind of reverting back to similar to 2.3). I assume it's been changed for a reason, if anyone can enlighten me on that one?
It now displays the limiter on page load, however it's showing all the products in the category or search results (lazy load helps here). If you then choose a limit number from the dropdown, the pagination works as expected and the page numbers appear at the bottom - yey!!
This fix is for the desktop view, the mobile will still show the max items as the limiter is hidden by CSS. I suppose it could be styled to show if you really wanted to.
I'm almost certain this was the default behaviour when I first installed 2.4.1 and then changed it to show only 12 per page, but I don't remember how to get it back.
Anyway, hope this helps others out.
/vendor/magento/module-catalog/view/frontend/templates/product/list/toolbar.phtml
<?php if ($block->getCollection()->getSize()) :?>
<?php $widget = $this->helper(\Magento\Framework\Json\Helper\Data::class)->jsonDecode($block->getWidgetOptionsJson());
$widgetOptions = $this->helper(\Magento\Framework\Json\Helper\Data::class)->jsonEncode($widget['productListToolbarForm']);
?>
<div class="toolbar toolbar-products" data-mage-init='{"productListToolbarForm":<?= /* @noEscape */ $widgetOptions ?>}'>
<?php if ($block->getIsBottom()): ?>
<?= $block->getPagerHtml() ?>
<?= $block->fetchView($block->getTemplateFile('Magento_Catalog::product/list/toolbar/limiter.phtml')) ?>
<?php else: ?>
<?php if ($block->isExpanded()): ?>
<?= $block->fetchView($block->getTemplateFile('Magento_Catalog::product/list/toolbar/viewmode.phtml')) ?>
<?php endif ?>
<?= $block->fetchView($block->getTemplateFile('Magento_Catalog::product/list/toolbar/amount.phtml')) ?>
<?= $block->getPagerHtml() ?>
<?= $block->fetchView($block->getTemplateFile('Magento_Catalog::product/list/toolbar/limiter.phtml')) ?>
<?php if ($block->isExpanded()): ?>
<?= $block->fetchView($block->getTemplateFile('Magento_Catalog::product/list/toolbar/sorter.phtml')) ?>
<?php endif ?>
<?php endif ?>
</div>
<?php endif ?>