Jesse Gorter explains why you shouldn’t overwhelm your dashboard chart users with colors:
In this example we use a signal color for the past too. Do you notice how the usage of green distracts from the current week which is a red? This suggest we are doing great overall even though at this time, we are doing not so great. It is up to you to decide what you want to communicate. If you are a sports team showing the rank during the season, only the current position would be important. In sales, having 30 weeks of outstanding sales above the target and the current week selling slightly under, it would make sense to show the signal color for the past.
Not to mention making it easier for people with CVD to read your report, something with which the red-green scheme does not do great.