• bug fix
• BC break? yes

By documentation (more info: https://www.php.net/manual/en/function.idn-to-utf8.php) the domain xn--tst-qla.de is same as täst.de, but Nette Url claims that it is a different URLs:

$url = new Url('https://täst.de:443/cart');
$url2 = new Url('https://xn--tst-qla.de/cart');

$url->isEqual($url2); // false

This modification adds automatic conversion of IDN domains to UTF-8 format (if an extension is available). Prior to conversion, the use of IDNs is detected to maintain maximum performance.

If a particular PHP does not have an extension, it can be replaced by the symfony/polyfill-intl-idn package.

Thanks.