Is there a specific reason why the backslash escape character is not working when trying to mask the @ symbol in PHP?

The backslash escape character (\) is not working to mask the @ symbol in PHP because the @ symbol is not a special character that needs to be escaped in PHP strings. To solve this issue, you can simply use single quotes ('') instead of double quotes ("") to define the string, as single quotes do not interpret special characters.

$string = 'user\@example.com';
echo $string;