When I am charging my right AirPod and try using my left one I can’t hear anything

So I have had my AirPods for a year now and I have always had this problem when I am charging my right AirPod and try using my left one I can’t hear anything but when I use my right one and left one is charging it works and when they are together they are good. Does anyone know how to fix this problem?

[Re-Titled by Moderator]