i have no idea why this is the case, and no idea why this COULD be the case. anyways check this out if you wanna feel like you're doing turbo business
call me a dork, but I always really like reading the credits and dedications for games, especially indie games. In Balatro's, I happened to notice LocalThunk [the dev] credits some other source with the music (can't remember who off the top of my head, I'm typing this at work), but mentions the score is "modified with permission," or something like that.
so it could just be that the original song was composed at that speed, and LocalThunk wanted something a little slower and vibier for the game, and that's why it's slowed during your actual gameplay. several folks in the comments were also mentioning file size as a reason, and I could totally see that as the case, too. Balatro takes a really tiny amount of memory to play, especially in 2024.
anyway, no matter the reason, I'm just stoked to see so much of cohost enjoying Balatro!! it truly is a phenomenal roguelike and I highly encourage everyone who hasn't to check it out