Why my Battery status color in the menubar is Red while it is charged more than 20%?
This malfunction is most likely the case due to the fact that the battery is no longer functioning properly, it can no longer hold a full charge nor charge properly. This means that its possible shows in red because it is at half of whatever the reduced battery life is (that could be anywhere from 50%, or even 70% cut down from the original battery life).

I highly recommend you go to an Apple tech support employee at one of Apple's stores. You will have to wait a bit for help, but I have a strong feeling that they will tell you the computer needs a new battery.