Brought my camera last summer. So this is my first real cold spell. I have the same issue with my 12 off 2c pro units for the last few days whilst if become cold -2 Celsius. They become moist on the front of the camera and all footage is un viewable. Cure is to wipe them but that is clearly
showing the flaw of these units. Awaiting reply that makes sense from Eufy. How can security cameras be sold that can’t see when it’s cold !!!
Mine is the opposite when i put the spotlight on the the vision goes foggy. The IR doesnt seem to help either. With both off the fog disappears. Daytime vision is great.
I have had exactly the same issue, I had immediately just put it down to a change in the temperature.
I was waiting to give it some time to see if it would pass, and it didn’t. After reading this post, I saw somebody mention a faulty IR, so I decided to switch off the night vision and switch it back on…… And the image immediately cleared up, and the fog disappeared.
I was very sceptical that the camera was faulty and believed it was Just the change in temperature causing fog on the lens. Unfortunately, now it’s clearly faulty camera. 
I agree, I have had the 2c pro kit for a week, useless at night, they all get foggy lenses on the inside and there is what looks like swarms of insects visible, but can’t physically see any outside.
Also the spotlights are barely visible and the motion detection is hit and miss.
I do not recommend these Eufy products. Can’t believe they are bosting about winning awards??
Eufy is refusing to replace my two outdoor cameras that are two years old this month. These cameras are rated IP67, which means:
“Protection against water and liquids, up to and including immersion in up to one meter of water and complete protection against ingress of dust and airborne particles”.
It’s infuriating that they have stated their cameras are IP67 rated when clearly they’re not and refuse to replace them after only two years. I will NEVER recommend this product to anyone.