Comment 9 for bug 1871801

After doing some more testing, I am not able to reproduce the problem... After installing the russian language pack and running 'LANGUAGE=ru_RU.UTF-8 update-manager -d' everything is displayed as expected (see screenshot).

Could you please verify the package versions you've been using? Here are mine:
#:~$ dpkg -l | grep update-manager
ii python3-update-manager 1:20.04.10 all python 3.x module for update-manager
ii update-manager 1:20.04.10 all GNOME application that manages apt updates
ii update-manager-core 1:20.04.10 all manage release upgrades
#:~$ dpkg -l | grep ubuntu-release-upgrader
ii ubuntu-release-upgrader-core 1:20.04.19 all manage release upgrades
ii ubuntu-release-upgrader-gtk 1:20.04.19 all manage release upgrades