preg_replace_callback not working

I’ve a problem inside my block frontend code (php)

In this case ‘query’ attribute is ‘AUTH:{AUTH}’

<?php
$query = $attributes[‘query’];
$q = preg_replace_callback(‘/{(\w+)}/’, function($matches) {
return $matches[1];
}, $query);
echo ‘<div>’.$q.'</div>’;
}
?>

This code is not working.
I tried the above code in more than one php playground and it’s working correctly.
The result to the above snippet must be that $q is ‘AUTH:AUTH’.
This is a simplified case, the above inline function must return a more complex value.

Thanks.