/usr/lib/thunderbird/ is in thunderbird-locale-hu 1:38.6.0+build1-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/thunderbird-addons/extensions/
/usr/lib/thunderbird-addons/extensions/langpack-hu@thunderbird.mozilla.org.xpi
/usr/lib/thunderbird/distribution/
/usr/lib/thunderbird/distribution/searchplugins/
/usr/lib/thunderbird/distribution/searchplugins/locale/
/usr/lib/thunderbird/distribution/searchplugins/locale/hu/
/usr/lib/thunderbird/distribution/searchplugins/locale/hu/eBay-hu.xml
/usr/lib/thunderbird/distribution/searchplugins/locale/hu/google.xml
/usr/lib/thunderbird/distribution/searchplugins/locale/hu/sztaki-en-hu.xml
/usr/lib/thunderbird/distribution/searchplugins/locale/hu/vatera.xml
/usr/lib/thunderbird/distribution/searchplugins/locale/hu/wikipedia-hu.xml