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