This is a follow-up to earlier reports, which can be found here and here.
Update (4/5/2020, 4:20 PM PST): 1st Playable is confirmed to be the developer of the game, as per their Twitter. They deny blockchain functionality, and refer to "frustrating" distribution problems with the game. Thanks to @Evit_cani for the tip!
Sounds like early reports might have been cooking up trouble. As it turns out, the inexplicably mysterious Cooking Mama: Cookstar likely isn't the cryptocurrency mining tool some say it is.
Dataminer SimonTime posted his own independent research on Twitter. Based on his own discoveries, Cooking Mama: Cookstar has no blockchain functionality anywhere within the game. Not only that, but there are no indications of cryptocurrency miners in the game itself.
So, then, why is the game allegedly overheating Switches and draining batteries? Twitter user @Evit_cani has a potential explanation in their breakdown of the game.
They go on to report that overheating Switches, from what they've read, are occurring with players that have run the game in handheld mode. Additionally, they point out that accounts of the game stealing personal info is pure speculation - effectively putting the kibosh on that line of thought. Also worth mentioning is that the Switch's GPU isn't powerful enough to effectively mine any sort of crypto.
Another dataminer, Smellyfeetuhave, has corroborated SimonTime's story as well.
By their reports, Cookstar looks to be an average "generic Unity shovelware" game - which really does solidify the Switch as the next Wii, doesn't it? Joking aside, it seems like there isn't anything in the game's files that could be hazardous to your Switch or your personal info.
This leaves us with a story that, while admittedly less exciting, is still a bit of a strange saga. There's still no explanation for the pulled websites, the lack of advertising, or any marketing on the end of any involved party - outside of a Koch Media press kit. There's also no explanation for 1st Playable being erased from some classifications of the game, or why they would develop a game historically developed in-house. We can, however, confirm that Cooking Mama Ltd. has still gone by Office Create as far back as 2017's Cooking Mama: Sweet Shop.
Whatever the case may be, the saddest part of this whole affair is that there are people who really do want a new Cooking Mama (myself very much included.) Hopefully, we gain a bit more clarity on this in the near future, and the very finished Cookstar is a bit more easy to get our hands on.