Comment # 1 on bug 1229022 from Christophe Marin

The KlocalizedString warnings are just that: warnings informing something is
wrong in the keepassxc code (I can't reproduce with keepassxc 2.7.9, even after
forcing my language)

Did you change keepassxc settings? (e.g. autostart and tray icon settings)

If in doubt, kill the keepassxc process, rename the ~/.config/keepassxc folder
and try starting it again.