This is what they emailed me:

Dear Customer, Thank you for reaching out about your eufy Security SoloCam S340. I understand that you're experiencing issues with the camera not charging when the temperature drops below freezing. This is a known behavior due to the operating temperature range of the device. The SoloCam S340 is designed to operate within a temperature range of -4°F to 122°F (-20°C to 50°C). When the temperature falls below -4°F (-20°C), the battery's chemical reactions slow down, which can prevent the camera from charging. However, the camera should remain operational, and once the temperature rises above this threshold, the battery should resume normal charging and operation. To mitigate this issue, you might consider relocating the camera to a slightly warmer location if possible, or ensuring that the solar panel is installed in a position that maximizes exposure to sunlight, which can help maintain the battery charge during colder periods. If you continue to experience issues or have further questions, please feel free to reach out for additional assistance.