Quality Changes during session /tabbing out of Spotify-Window

[MusikNiklas]

Hello Community,

my problem is that the quality of the song, that I am listening to, is changing to a lower quality, when I tab out of Spotify and go to the browser etc.
It takes at least 3-4 sec until the music sound/quality changes and only switchs back to the normal quality, when I get back to spotify. 
I have a Windows 10 Laptop, if this information is necessary.