JuniorTheoryCommon

What does the program print?

PHP

<?php

$name = '<b>Ann</b> & "co"';
echo htmlspecialchars($name), "\n";

Ann & "co"

Expecting quotes to stay as they are when no flag is passed: the default flags encode " as ", and since PHP 8.1 they include ENT_QUOTES, so ' becomes ' too.
Expecting htmlspecialchars to strip the tags: it removes nothing, it turns < and > into < and >, and the browser then shows the tag as text.

JuniorTheoryCommon

PHP

<?php

$name = '<b>Ann</b> & "co"';
echo htmlspecialchars($name), "\n";

Ann & "co"

Expecting quotes to stay as they are when no flag is passed: the default flags encode " as ", and since PHP 8.1 they include ENT_QUOTES, so ' becomes ' too.
Expecting htmlspecialchars to strip the tags: it removes nothing, it turns < and > into < and >, and the browser then shows the tag as text.