itch.io

had the same issue.
The issue started at the second run, so I already had updates.
I'm guessing the issue comes from the updagre "+1% change money x10".
The money normally goes up, but sometimes goes down by damage (10 in my case) - block health (money gained, let's take 2 as example) * 10 + 10 (for some reason) = -70 money gained. That formula followed up when the block had more health later in the stage.