Macbook Air battery icon shows wrong percentage

Happy owner of Air 13"

A few days ago, I have found a difference in the battery percentage between icon in the top bar and system monitoring application.

let's say, icon shows 65%, but if I open "system monitor", it says: 60%. Also I have noticed that % digit next to the icon appear to be frozen. It could show some % pretty long period of time, however system monitor shows an actual data, which is different.

why is that, how to fix/avoid that?

the only way to sync them again is to switch the % off and to turn it back on.