ambient light

I do a bunch of flying during the later part of sunset. I keep getting a message on my screen saying Ambient light to low (I know the forward vision sensors need good lighting due to a conversation with DJI but they never finished answering me). So my actual question is (because I guess I am...

Couple of days ago I did a small test flying over an empty field during the night it was just after 10pm so not completely dark yet, I had my vps ON, landing was rather easy as usual, no surprise at this point but... 9min flight - no wind at all, perfect weather condition, no strong lights...