Has anybody found a way to fix Windows 10 not displaying flag emojis properly?
Here, the country code (UA) appears instead of the flag (). I believe this is moreso a problem of Windows 10 rather than a problem of Anki.
Lack of support for emoji flags in Windows is a long-time issue. Your best bet is to use an image instead. For instance, I just copied the flag out of your post, and it pasted into Anki as a png.