Well that applies to far more than this subject.

I don't think the line is that fine in that case, considering all random mechanics in Balatro give ephemeral rewards that only last until the end of a run, which is an isolated instance of a game with limited playtime, those mechanics cannot be paid for with real money, the resulting rewards cannot be sold for real money or traded with other players, and generally cannot affect any other players in any way, not even visually through cosmetics.

As far as I know, Balatro is only really being targeted because it's stylized after poker, with the enforcement having no actual understanding of what the gameplay looks like.

I think at bigger risk from actual laws would be MMORPGs where you can get random loot drops from enemies/chests, and those also tend to have markets where people grind valuable drops and use in-game trading to transfer them to other players in exchange for real money.