Usually, it comes after several attempts at starting the vehicle, or after you had to call AAA to jump a dead battery. Sometimes it's a bad cell, sometimes the battery keeps dying, and sometimes ...
Instead of dropping a battery, an object – in this case a brass slug – was dropped onto both good and bad batteries. There was no difference. Even after holes were drilled to vent any gasses ...
A lot of the trouble with the iPhone 13's battery can be fixed by disabling 5G, but if you don’t want to do that, there are a few other tricks you can try to increase your bad battery life.