MacBook Air 2015 MagSafe charger is too hot to touch

In the last couple of weeks, I've noticed my charger connector (the part which connects to Mac) is too hot to touch and also there are some pins a bit burnt (it is happening slowly but getting visibly worse). Charging ability is unchanged but I really like this machine, otherwise, it is working fine. I have tried to clean the patches. It is extremely hot only when not fully charged when fully charged it is normal. What could I do? I guess it is not exactly harmless for the machine.