Steps to reproduce the issue

• Current Staging or apply PR #18221
• Set error reporting in global Joomla configuration: Maximum.
• Go into 5 published articles and add this text somewhere in the article text:

1/17

• Save articles.
• Go to frontend and search for

1/17

• Any second hit has no title.

• Several times:

Warning: preg_replace(): Unknown modifier '1' in \components\com_search\views\search\view.html.php on line 271

Reason:

See changes in https://github.com/joomla/joomla-cms/pull/18221/files

$needle = str_replace('/', '\/', $needle);

The problem is that this line is inside a foreach loop. So $needle becomes:

1. search hit: 1\/17 (OK).
2. search hit: 1\\/17 (PHP-Warning. Empty title.).
3. search hit: 1\\\/17 (Not really OK but no Warning).
4. search hit: 1\\\\/17 (PHP-Warning. Empty title.).
   and so on.