/usr/share/php/Symfony/Component/Translation/Loader/ is in php-symfony-translation 3.4.6+dfsg-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/Symfony/Component/Translation/Loader/ArrayLoader.php
/usr/share/php/Symfony/Component/Translation/Loader/CsvFileLoader.php
/usr/share/php/Symfony/Component/Translation/Loader/FileLoader.php
/usr/share/php/Symfony/Component/Translation/Loader/IcuDatFileLoader.php
/usr/share/php/Symfony/Component/Translation/Loader/IcuResFileLoader.php
/usr/share/php/Symfony/Component/Translation/Loader/IniFileLoader.php
/usr/share/php/Symfony/Component/Translation/Loader/JsonFileLoader.php
/usr/share/php/Symfony/Component/Translation/Loader/LoaderInterface.php
/usr/share/php/Symfony/Component/Translation/Loader/MoFileLoader.php
/usr/share/php/Symfony/Component/Translation/Loader/PhpFileLoader.php
/usr/share/php/Symfony/Component/Translation/Loader/PoFileLoader.php
/usr/share/php/Symfony/Component/Translation/Loader/QtFileLoader.php
/usr/share/php/Symfony/Component/Translation/Loader/XliffFileLoader.php
/usr/share/php/Symfony/Component/Translation/Loader/YamlFileLoader.php
/usr/share/php/Symfony/Component/Translation/Loader/schema/
/usr/share/php/Symfony/Component/Translation/Loader/schema/dic/
/usr/share/php/Symfony/Component/Translation/Loader/schema/dic/xliff-core/
/usr/share/php/Symfony/Component/Translation/Loader/schema/dic/xliff-core/xliff-core-1.2-strict.xsd
/usr/share/php/Symfony/Component/Translation/Loader/schema/dic/xliff-core/xliff-core-2.0.xsd
/usr/share/php/Symfony/Component/Translation/Loader/schema/dic/xliff-core/xml.xsd