Bug/Mistake in Report

In the Report “Transaction of category” there is a failure.

Where you can see below of the Diagramm how many percent of the month before you have spend, the percentage of the outgoing is wrong.

I want to know for example outgoing in Oktober 1000€ compared to outgoing in November 1500€.
In this case it Must Show +50%more than the month before.
But it shows minus…% than the month before.

I think this occurs from the case that it includes in the calculation the income. Because in November I got the Christmas money.
But that shouldn’t affect the income in the comparison of the outgoing per month!!!!