/usr/lib/ is in thunderbird-locale-ro 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/ro/
/usr/lib/thunderbird/distribution/searchplugins/locale/ro/eBay.xml
/usr/lib/thunderbird/distribution/searchplugins/locale/ro/yahoo.xml
/usr/lib/thunderbird/distribution/searchplugins/locale/ro/amazondotcom.xml
/usr/lib/thunderbird/distribution/searchplugins/locale/ro/wikipediaro.xml
/usr/lib/thunderbird/distribution/searchplugins/locale/ro/bing.xml
/usr/lib/thunderbird-addons/
/usr/lib/thunderbird-addons/extensions/
/usr/lib/thunderbird-addons/extensions/langpack-ro@thunderbird.mozilla.org.xpi