Yeah, it looks similar to the line in that image. 48" screens are definitely not banding immune.This kind of worries me. I was pondering if I should have gone for the 48" CX since smaller sizes are supposedly less prone to display banding... Is it perhaps something similar to what's seen here on the far right?
As for the other thing... it's the first time i'm reading about a grid issue on bright content (and it sounds even worse since it's probably easier to see too).
As for the other issue, it's noticeable when panning the camera across a reasonably sized very bright sun/cloud which is solid in colour in a HDR game basically (on either my PS4 or PC, so it's not the source). Admittedly, most games wouldn't pan over the sky fairly fast like that(nor would it be the focal point of the shot if they did), so I guess it's not as noticeable as you'd think initially, but it's still annoying to know it's an issue. Not really noticed it in SDR (though my OLED light is set rather low for SDR since I mainly watch in the evening) or when watching movies.