The flag icons in the language switchers can be replaced with an own image as described in the following:

1.  Upload the flag icon (image or SVG) to the /assets folder of your theme and copy its new source for later use.
   
   
2. Add the following custom CSS to your theme's styles file or in the "Switcher Configurator -> Custom CSS" section of langify:
   
   

   .ly-flag-icon-<LANGUAGE-CODE> {
       background-image: url('<NEW-ICON-SOURCE>') !important;
   }

   
   
3. Replace the <LANGUAGE-CODE> placeholder with the language code (in lowercase letters) of the related language which you can find in the "Languages" section of langify and paste in the new icon URL for the <NEW-ICON-SOURCE>.