Has your income gone down due to any situation, and does the change make a difference in the income level we consider?
No, not really.
One final question: do I need to file an appeal if I'm asking for a new decision, because I now earn less?
You don't need to file an appeal if you're requesting a new decision because you experienced one of the events listed and, it made your income go down, or if you've shown us the information we used is wrong.