My "Low Visibility" in broad daylight problem solved:
I know this is an old thread, but I got the same "Low visibility- Fly with caution" warning when flying my
Mini 3 Pro in the middle of the day and my online search led me here.
To set the stage, the Mini3P was flying perfectly without problems for a while until a recent RTH mishap that landed it on the roof and fell about 10 feet to the ground. The propellers, propeller guard, and the landing gear were damaged but no other damage was visible. So I replaced all the damaged parts and recalibrated everything via the controller and it then flew perfectly as usual, except that's when I started to get the occasional "Low Visibility" during mid flight. There are no other warning , alerts, or anything. Photos and videos are all perfect and the take-off, landing and RTH all continue to function as always.
Cleaning the lenses and calibrating the vision system with DJI Assistant 2 did not make a difference. I was just about to pack it up and send it in to DJI for repair, a Eureka moment hit me that I remembered the new landing gear is different than my old one, the new one has LEDs and a small battery holder in the middle, it is small and unassuming, so I did not think of it at first, but as soon as I removed the landing gear and flew it again, lo and behold, that was it.
I did further testing with this and found a consistent pattern that whenever the aircraft tilted forward from any quick change in motion or big change of direction, the vision system or the OA is somehow partially blocked by the landing gear's battery box, thus triggered the occasional "Low Visibility" warning.
Since my Google search led me to this thread 3 years later, I thought I leave my finding here for someone else who encounters this issue in the future.