Many years ago when ships carried radio officers, it was my habit after the last watch of the day to go on the blacked out bridge and chat with the navigation officers over a cuppa. Invariably the radar screen would be misadjusted, with the sensitivity and brightnesss turned down. I would reset the display only to be faced with complaints from the navigation officer that looking at the radar screen set correctly destroyed his night vision. Their preferred setting was to have no clutter at all visible and large targets barely showing on the screen. It kept the brightness down but meant that small vessels such as fishing boats would go completely unnoticed unless their navigation lights were spotted.
Moving on several decades. Helicopter flying in the dark, crew wanting to keep their night vision as sharp as possible for a forthcoming landing, all the instrument lighting turned down as low as it will go. It seems a similar situation to what I experienced years ago but in a different environment. Everything could have been working just fine, but to see fine detail on a radar display, you need the brightness turned up more than is compatible with maintaining good night vision. I know there are night display modes that are supposed to help with this problem, but established habits are hard to break. None of the navigation officers I worked with could avoid tweeking the radar display after I had set it up correctly.
Just another one of those human factors that could be relevant.