So, Been playing some income and chill classic, and i just noticed that if you have mythium left that autosend is not able to spend, you get the penalty and the game considers that you saved.
Scenario example:
You have giant snails, manually send all 8 giant snails, when wave ends you have 33 mythium, autosend can't spend it, BOOM no gold rush gold.
Same applies with any spam send you do, can get the penalty quite easily tbh.