Metallica had themselves one hell of a 2021 in terms of streaming on Spotify. The band was streamed 1.3 billion times across 58 million listeners, which works out to about 22.4 songs per listener. Metallica was streamed 1.1 billion times in 2020 and I'm sure the year-over-year increase probably has at least a little to do with their 2021 Black Album reissue. It's also worth noting that both "Enter Sandman" and "Nothing Else Matters" are approaching the one billion streams each mark, with both hovering around 750 million apiece (the former at 780 million and the latter at 706 million).
Maybe they'll get even more streams this year if a new album does indeed surface?