Why does the screen around become a little darker when opening AIMP?

Question

Windows

Look, Aimp is sitting in my system, I open it, and the screen around becomes a little darker, or more contrast.
I minimize - the picture becomes a little lighter back (desktop picture, icons).
If you click on the desktop while open (remove focus from the Aimp window), nothing happens.
There is no such thing as dynamic brightness and contrast.
There is a TV 32", fullHD.
Built-in video card on AMD Radeon.b HDMI
What's wrong with me?