Why emoji counts can differ from code-point counts
A visible emoji can contain several code points joined into one grapheme, including flags, skin-tone modifiers and family ZWJ sequences. The counter groups supported grapheme sequences so a single visible emoji is not automatically counted once per underlying code point.
Counts are grapheme- and qualification-aware
A joined emoji, flag, keycap or modifier sequence remains one grapheme. Fully-qualified RGI forms are distinguished from related forms missing presentation selectors.