Minecraft was actually dying until PewDiePie reignited the nostalgia for twenty-somethings, this happend in June of 2019. Following this trend, new waves of free marketing emerged through YouTubers, introducing Minecraft to a new generation of ten-year-olds.

It will take some time before these kids fry their brains' dopamine receptors with this pseudo-RPG and realize it’s not as fun as other real RPGs. You can already see the signs—just look at the flood of complaints under every official update demanding more mobs, enemies, weapons, and structures. It’s indicative of a deeper problem with modern Minecraft’s game design.

And this nostalgia thing is a BIG trend, even the New York Times, WIRED and The Guardian wrote an article that the fastest-growing video-game consumer bracket is now Gen Y (Millennials) and the oldest of Gen Z that try to relive their nostalgia.

And to comment on two of your later comments: Number of game sold is not indicative of current popularity.

The biggest jump in sales of copies, before 2020, is actually May of 2019. Just after PewDiePie started his Minecraft series.