https://bugs.winehq.org/show_bug.cgi?id=47302
--- Comment #6 from Fabian Maurer dark.shadow4@web.de --- This key should be updated when setting LC_ALL, like for example with LC_ALL=de_DE.UTF-8.
How do I do that? (fresh WINEPREFIX)
You mean how to create a fresh WINEPREFIX? See https://wiki.winehq.org/FAQ#Can_I_store_the_virtual_Windows_installation_som.... Either delete .wine (removing everything inside it), or use a different folder.