Why is dark mode not black?
Dark mode implies the use of very dark hues, just not necessarily pure black. The emphasis in dark mode is on contrast. So as long as you have enough contrast, you will OK.
Is dark mode pure black?
If you have used the previous Google Dark mode, then you will know that it was actually a shade of Gray. The new dark mode is pure black.
Is dark mode harmful for eyes?
Dark mode may work to decrease eye strain and dry eye for some people who spend a lot of time staring at screens. However, there's no conclusive date that proves dark mode works for anything besides extending the battery life of your device. It doesn't cost anything and won't hurt your eyes to give dark mode a try.