Cleaner costs are a thing that only really makes sense in stealth. You're already shooting cops en masse in loud, so why would a civilian death matter? There's no traces to hide or backstories to rewrite in a full blown loud heist, so why do I have to pay for these cleaner costs? It's not even really about the cash you lose since that will barely matter at a certain point into the game, it just doesn't make sense.
This mod simply disables cleaner costs when the game is not in a stealth state. The trading penalty will still apply and you will still lose money for killing civilians in stealth like normal.