Power percentage is not increasing (and not decreasing) while on charge.

Hi all,

I have problems with my macbook pro 2015 15' after I upgraded os for Catalina 10.15.5. The problem is that macbook doesn't increase or decrease power percentage while on charge, but when I plug charger out, battery level goes down. When I then plug in, battery percentage remains on the same level.

Btw, sometimes it is shown at toolbar that mac is charging, sometimes it is not (see attachments).

Please, help me to investigate this, thank you in advance!