Revenue compare logic for this month vs. last month

[flowdee]

When switching the date range to "this month" the comparison shows 25% over previous 18 days (it's the 18th of the month).

But in my opinion the numbers should be compared to the complete previous month and not the last 18 days. Cause that's the reason why I select "this month" in order to get the current data AND compare it to the last month.