Thank you for playing!
Yeah it seems the upgrades being unclear has been the most common pain point I have heard for our game, which is totally fair. It's a bit of a "hidden knowledge" right now even if you can see the description when you hover the mouse over the buttons if you play on PC. But since it's not stated in game either so I think a lot of players miss that.
We plan to put out a post-jam update with things updates to the UI etc. so you can consider adding the game to your collection and be notified when we made updates for the game 😄