Before the total phone reset(factory reset,reboot) when was playing a game after a while screen was going like in a standby mode, almost black,but game was continuing to be idled and had a little lock on screen only had to swipe to make screen normal mode.it was with smart lock option ..whatever I change now and set it up it won't do that anymore ..either diminishes the light very little but still too bright(in case I leave it during night time) or have option to put screen saver "photos"(from gallery like a showdown)or "colors"(which is like a dark blue and black wave continously moving).I have no power saving on.."never sleep"option active from developer tab and a Samsung j4+ phone