Just before the end of March, Cooking Mama: Cookstar officially released for the Nintendo Switch via the digital eShop. Since then, the game has mysteriously gone missing. It's no longer anywhere to be found in the Nintendo eShop and some online retailers, such as Gamestop, are no longer selling physical copies.
However, with the game's release date depending on region, it's still available to be pre-ordered in Europe from the likes of GAME. Physical copies are still available to order from EB Games in Australia. All in all, it's inconsistent and confusing. Nobody seems to know why the game's release was essentially walked back on.
There's speculation that the game was hiding some dodgy cryptomining code. The developers of the Cooking Mama: Cookstar responded to the allegations as such (via Nintendo Everything):
"As the developers we can say with certainty there is no cryptocurrency or data collection or blockchain or anything else shady in the code. The Nintendo Switch is a very safe platform, with none of the data and privacy issues associated with some mobile and PC games."
Investigation has proven that the game doesn't feature any code of the sort, however, may have at one point. It's thought that cryptomining code was shoddily removed just prior to launch (via @DirectFeedGames). On account of this, the game drastically drains the console's battery. That's likely why the game was removed — but it's still just speculation.
It's all certainly peculiar. Cooking Mama: Cookstar remains absent from the Nintendo eShop to this day. We will be sure to update you if and when it's relisted.