Works fine to me.
Good use for me reading Light Novel and Manga/manhua/manhwa to force dark mode on website and scan website that don't have dark mode.

Suggestions:

1. a right-click context menu with "exclude from this site" (it is useless on sites that are already dark), like this one has: https://addons.mozilla.org/en-US/firefox/addon/dark-mode-webextension/

2. a shortcut toggle like Dark Reader (https://addons.mozilla.org/en-US/firefox/addon/darkreader/) has.

Works just after install. Love it!

При нажатии на кнопку дополнения, чёрное окно становится светлым, а светлое тёмным. Так происходит потому, что режим работал до открытия второго окна и происходит рассинхронизация.

Just added it and it worked instantly. satisfied so far