Try this one:
+3000 stars
+500 forks
https://github.com/darkreader/darkreader
I just tried it and it's working perfectly. Below is a snap of the Meta section that I took just now:
You can even adjust brightness, contrast, and many other settings from the extension settings. It also has a light mode that makes the colors a bit dim than usual which means that if you don't turn the extension off and switch from dark to light, you will see dark mode going off but the colors will still be less brightened, easier for the eyes.
I like it more with the following settings:
Brightness: +50
Contrast: -50
Sepia: off
Grayscale: off
After that I changed it back to its original state, unfortunately being white tires my eyes a lot, but the black state was not very natural either, of course this is a matter of preference.
Many users may have been satisfied, but for me it was better to use the original state.
The black theme turns many areas dark, but I guess the fact that there were still some whites distracted me.