Unicode in .mcfunction file is not possible (For data packs/functions)

Unicode totally works when I write it in Minecraft itself.

But when I start using Unicode in a .mcfunction file for a data pack/function for example in a /tellraw command it will show me an error Message (Picture 1 [In German]) because the ANSI format doesn't support Unicode. But when I save my .mcfunction file in the Unicode format or in the UTF-8 format the file stops working completely.

Greetings