Thank you SO much!
I won't lie, the difficulty scaling, though existing, was quite rushed. Basically, the time it takes for a new customer to walk in slowly decreases, and in theory, it should reach a point where serving all customers is not possible, thus making you lose points until you lose, but I think something went wrong. I think I might be able to fix it, but I don't know if actually changing the lose condition would be fair game after submitting. I know bug fixing is allowed, but dunno about this.