I just got a surface laptop at a good price, display one.
It seemed to work perfectly, until I saw it on a grey background - I can see shadows of what was the background on this laptop in the store. Before I got it, a guy from the store said he cleaned it up completely, and I just had to finish the windows installation...
Has anyone experienced anything similar? Is this a BIOS issue or a display issue?
Quite possibly display. Often retailers have those units on 24/7 and about as often fail to make use of the tools to prevent this.
They probably did not have it cycling content and did not enable it to turn off screen.
I'd bet on display. It's very rare with leds, but months on the same will do the trick.
I say this having seen the problem on many of our tablets when I worked at Staples (we didn't have a screensaver tool for them and regulation was 24/7 screen on). Not on our pcs, but they always had a demo loop installed.