Running Android 14 and somewhat disagree. I have had 1-2 games running in the background after "exiting"/"quitting" the game and dropped from 80-90% battery to 30% in less than 2 hours. (GPS and Bluetooth both disabled). Battery dropped as though I was actively playing with the screen on during that time.
Killing apps has helped me with this issue, in general. However, for the offending game, setting "app battery usage" (specific to Android, not sure of iOS equivalent, if any) has helped better for this issue. Seems a lot of games are trying to load unmecessary stuff and/or sell usage data, despite exiting the game...
The last three sentences are not quite accurate. It's not necessarily that nothing existed before the the big bang. It's a singularity event where mathematically we can simply not know what existed at/beforehand that moment. It is somewhat comparable with the event horizon of a black hole.
There is something happening/existing, otherwise a black hole would not be able to occupy space or affect light. We simply do not have the ability currently to understand what that is.
By definition, that is not nothing. It is a that we cannot know/understand it, at that moment. Notably, a lack of evidence is not evidence of nothing.