Is this a game OST or something? I can't find anything about it!

It seems to be neither an anime nor a game. Maybe a guy working on his own: https://twinkle-japan.bandcamp.com/album/twinkle-1stbest-album

The title loosely translates to "Gao Gao Pyon Concerto for Bear and Rabbit · (by) twinkle"

Edit: it seems to be one of those weird guys who make remixes with anime voices in a "techno / dance" style. Some may be Japanese, some are Americans, it's a bit random.

https://twinkle130527.wixsite.com/twinkle/about

We mainly create moe-style cute tracks and denpa songs.

Participating in doujin events like M3 and Comiket.

We also host twinkle-organized live shows once or twice a year.

There are a lot of artists who do this, feel free to ask if you need more references.