As far as I know, there's no official documentation for it, but people noticed that it happened every month and that it would fix dead pixels (for example: http

As far as I know, there's no official documentation for it, but people noticed that it happened every month and that it would fix dead pixels (for example: https://www.4kshooters.net/2015/12/01/an-easy-trick-to-fix-dreadful-dead-pixels-in-your-sony-a7s-ii/ https://www.4kshooters.net/2015/12/01/an-easy-trick-to-fix-d...) I personally used this trick twice to fix dead pixels on my camera, so I can attest to that. For cameras without a mechanical shutter, there is instead an option to do it in the menu, for example : (https://helpguide.sony.net/ilc/2010/v1/en/contents/TP0003229312.html https://helpguide.sony.net/ilc/2010/v1/en/contents/TP0003229...)