I’ll have to revisit mine in a dark room setting tomorrow and see how it’s holding up but I’m sure it was way better than that. I certainly don’t notice it in games or when watching video. Obviously the blacks aren’t as good as on other models or types of screen, but as I don’t tend to use it in a dark room it doesn’t bother me that much.
It is standard for this mornitor if you look at reviews. It is worse in this monitor than in other IPS monitors, but it is a weakness (perhaps the only one) of this technology, on normal use you shouldn't notice it.
This is the RTings comment for the 27GL850-B
Unfortunately, this monitor has poor black uniformity. There's noticeable backlight bleed and clouding throughout. This might vary between units, so let us know if you get a unit with better black uniformity.
And this is for the 27GL83A-B (same panel):
The 27GL83A-B has poor black uniformity. There's visible clouding throughout and very noticeable backlight bleed near the top left corner. This may be distracting when watching dark scenes.