optiplex 7770 image retention

Hello

 around eight months ago I bought an optiplex 7770a AIO with a 4k OLED monitor. It is a computer that I use when I work at home.

Nevertheless, on the bottom left corner the windows icon caused a permanent mark on the screen. It is not visible if that area of the screen is pure white or pure black (I guess for the lack of light in the second case), but any other color will feature a white 'windows logo' visible mark. On the right bottom side, the square notification icon is also visible, but barely. After some time the icon is not shown (but I need to automatically hide the taskbar for that).

I could not imagine that the problem would show up so early. Is there anything I can try? Is there any hope of guarantee?

Thank you.