Question Decolorated rectangle on screen ?

[AxiMoV]

There´s a transparent rectangle that changes color depending on what´s behind. (Sentey ms-2710)

I´ve got a gtx 1060 6GB Aorus xtreme gaming.

PS: I´ve got another monitor plugged in and it works just fine.

Some pics:

https://ibb.co/9Z6g94P

https://ibb.co/5xx6CYG