Disabling the plugin would work - it won't be re-enabled on updates.

But what you're doing is wrong in general. There's a fine line between making layout overrides and hacking them to a point where they no longer should be layouts. For this purpose you should try to make your own component or find a 3rd party component that meets your needs.

To use `Pagination` class without causing conflicts with current component's links, pass the fourth argument when instantiating the class. This is a prefix to be used for generating links. Use the same prefix when getting input variables.

    defined('_JEXEC') or die;
    
    use Joomla\CMS\Language\Text;
    use Joomla\CMS\Pagination\Pagination;
    use Joomla\CMS\Plugin\CMSPlugin;
    use Joomla\CMS\Uri\Uri;
    use Joomla\Filesystem\Folder;
    
    class PlgContentPagebreakgallery extends CMSPlugin
    {
    	protected $app;
    	
    	public function onContentPrepare($context, &$item, &$params, $itemPage = 0)
    	{
    		if (!preg_match('#\{pagebreakgallery=\"(.*?)\"\}#i', $item->text, $folder))
    		{
    			// Shortcode not found.
    			return true;
    		}
    
    		// Remove the shortcode.
    		$item->text = str_replace($folder[0], '', $item->text);
    
    		// Check that we are on article view.
    		if ($this->app->input->get('option') !== 'com_content' || $this->app->input->get('view') !== 'article')
    		{
    			return true;
    		}
    
    		$imagesDir = '/images/' . $folder[1] . '/';
    
    		try
    		{
    			$images = Folder::files(JPATH_ROOT . $imagesDir, '(?i:.(jpg|jpeg|png|gif))$');
    		}
    		catch(\Exception $e)
    		{
    			// Directory doesn't exist.
    			return true;
    		}
    
    		if (!$pages = count($images))
    		{
    			// No images.
    			return true;
    		}
    
    		// Prefix used for pagination links.
    		$prefix = 'pagebreakgallery_';
    		$page   = $this->app->input->getInt($prefix . 'limitstart', 0);
    
    		if ($page > $pages - 1 || $page < 0)
    		{
    			// Image doesn't exist.
    			throw new \Exception(Text::_('JERROR_PAGE_NOT_FOUND'), 404);
    		}
    
    		$item->text = '<img src="' . Uri::root(true) . $imagesDir . $images[$page] . '" />';
    		$pagination = new Pagination($pages, $page, 1, $prefix);
    
    		$item->text .= '
    			<div class="paging">
    				<div class="pagecount">' . $pagination->getPagesCounter() . '</div>
    				<div class="pager">' . $pagination->getPagesLinks() . '</div>
    			</div>';
    	}
    }