Sound volume problem

Hello to everybody.
The last 6 months I face the following problem with MPC player.
Each time i use MPC for music or video when I put it in the bcakground or another app is in front of it the volume is decreasing to very low. When I bring it back in the foreground the volume increases.
Have anyone else faced the same problem?
I there any solution?

The player itself and the codecs don't change the volume in such a way.

It might be Windows that is doing it.
Right-click on Volume icon in the Windows system tray > Sound Devices > Communications > select "Do nothing"

Found the issue - On Lenovo laptops, Dolby Digital Plus or Dolby Atmos Speaker System has a "Volume Leveler" which is OFF by default ... when it is off (the default), the volume changes when window focus changes (no idea why). Switching the leveler to ON fixes the problem.