It's fine if you did it to test our their app and test out your skills, but as soon as you cashed out, you have become an unethical person. It's like if someone sent money to their own charity and then deducted that amount from their taxes. This is unethical.

I hope you understand the difference between getting something for free (using the app without ads) and taking something away (cashing out the money by gaming the system).

That money was meant for humans playing the game with merit based on math skills not merit based on software engineering.