battery - Which process is locking the camera?

There is a problem with my UleFone Armor 2 with Android 7.0 Nougat:

After using the camera some times, it stops working due to the inability to connect to the camera.

I tried killing the camera application, but it does not yet unlock the camera. And the battery manager suggests that the camera was permanently on since the time it has stopped working.

A simple reboot does solve that problem, but rebooting is a seriois violation of an important Linux philosophy, which states that rebooting is never a good method of solving problems and should be avoided wherever possible.