Video storage without WiFi
A micro SD card is necessary if you want the camera to store motion detection recordings without WiFi (only for WiFi cameras) nor 4G (only for 4G cameras).
For more details about using a micro SD card in the camera, please check the link below.
The camera can't know the time without WiFi/4G network. So the recordings will not have a timestamp and will be saved into the default date. All the offline-recordings will be saved on the default date instead of the real date.
Usually, the default date will be 1st January 2021 (or 31st December 2020). To check your camera's default date, you can take the SD card out and read it on your computer. There should be a file named as a very old date. You can find all your offline videos there.