Let's be honest, dark mode just looks super amazing, dark mode does offer something different that feels mysterious and new. Dark mode apps can prolong the battery life in our gadget It will save some but not much. If the device has an AMOLED screen then it will be more than if it has an LCD screen. The reason is because the LCD screen has to also have a backlight to shine through the pixels and it always shines. An OLED produces it own light generation with each pixel so when they go black the light is going black also.
However, not everything about dark backgrounds is good. For example, when you are using a device in a well-lit room or in direct sunlight, text positioned on dark backgrounds can be difficult to read. So the only reason not to implement a dark mode is when you're certain your app is exclusively being used during bright daylight, but this is rather exceptional.