It's been 6 months since Capcom announced Street Fighter 6 had sold more than 2 million copies, so it's safe to say sales have slowed down a lot even if the game passed a new milestone earlier this month.
Because the Japanese publisher reveals that Street Fighter 6 now has passed 3 million copies sold. This number is expected to grow even further, however, as Capcom reiterates the game will get a lot more content in the future, so we'll see where it stops.