When the camera's charge or battery level is low, it automatically reduces the length of videos.
It will be necessary to replace the batteries and change or charge the external power supply.
Your camera is not broken.
The visible moving part is an IR-Cut filter and is designed to float freely when not in use.
During the day, the camera uses the IR-Cut filter to filter out IR light ( fully covering the lens) So it does not distort the colors of images as the human eye sees them.
When the camera is in night mode, the IR-Cut filter is removed, allowing the camera to work fully in the dark.
This is an Excel file that allows yout to evaluate your consumption by selecting a camera model, the type of power supply as well as the number of photos taken during the day and at night.