Description:
------------
Using DomDocument to recover malformed XML (mismatched tags). In an XML file, AFTER mismatched tags are repaired (but not before), & is improperly stripped from the file.
Note, I selected 7.4.1 above, but I've tested this only in 7.4.0. But this is a longstanding bug going back to at least 7.2.

You can also see an example here:
https://code.sololearn.com/wAQh3FwVdYGO

Test script:
---------------
<?php
$d = new DomDocument();
$domDocument = new DOMDocument( '1.0', 'utf-8' );
$domDocument->recover = true;
	  
$xml = <<<EOT
<?xml version="1.0" encoding="utf-8"?>
<xml> Amp: &amp;
<foo> baz: <bar>foobar</foo></bar>
No amp? &amp;
</xml>
EOT;
$domDocument->loadXML( $xml );
echo "<br><br>";
echo htmlspecialchars( $domDocument->saveXml());
?>

Expected result:
----------------
<?xml version="1.0" encoding="utf-8"?> <xml> Amp: &amp; <foo> baz: <bar>foobar</bar></foo> No amp? &amp; </xml>

Actual result:
--------------
<?xml version="1.0" encoding="utf-8"?> <xml> Amp: &amp; <foo> baz: <bar>foobar</bar></foo> No amp? </xml>