Hey!
TL;DR: Played a bunch on PC, launched at laptop and saw there's no save, launched on PC again and there's no save either.
I've been enjoying Balatro mostly on my PC since the relase day. Today I downloaded it on my laptop and launched the game. I figured the Steam Cloud would handle things, but to my disappointment it wasn't the case. I remember seeing unlocks for a few things, but my decks weren't there and the collection got rest. I didn't start a new run and just closed the game. Tonight I got back to my PC and launched the game, only to notice my unlocks got wiped here too.
As you can see in the screenshot, the game still knows which stake difficulty I reached, but the collection and the decks got reset. Seems like a weird issue between a local save and the Steam Cloud save.