These lists compile the collective 2020 new-music listening of music fans in every country where people use Spotify, and in the fan communities for ~4000 genres and other genre-shaped distinctions.
The songs in each list are scored and ranked by a combined weighting of a) their absolute popularity with those fans and b) the share of the song's global listening that those fans account for. (And then filtered to one song per artist.)
This means, for example, that The Sound of Belarus 2020 is the music that defines, unites and distinguishes Belarusian fans, whether that music comes from Belarus or not.
Likewise, 2020 in Glitchcore is the music that fans of glitchcore loved, whether it's glitch or core or not.
To be eligible, a song must have been released on or after 2019-12-01, as best our data can tell, so that's why no "Watermelon Sugar".