It breaks most pages I tried

It could be better but it distorts some pages and makes the opening of pages heavy. He needs adjustment, he's got good potential.

Firefox slowed too much, but nice idea, I'll look at it when it will be usable.

Great for eyes health.

2 stars for effectively giving me the ability to put dark mode on any website.
-3 stars for
1) making all my tabs run slower...significantly slower
2) not honoring my preference of not running the addon on certain sites. After setting a site to not use the addon when I return to the page, the addon will still sometimes applying theming to the page...sometimes incompletely. This sometimes caused text to become unreadable.

A change could be made to the addon to correct this...default to off. Let me set a preference for if I want to apply dark mode or light mode, and then let me turn it on rather than force me to turn it off when it doesn't work for a site. This would default to the addon doing nothing on any sites until I explicitly say I want to use it there. You could even set it so I can choose whether the addon is used by default or not used by default. Options are always good.
I have uninstalled this addon because of these problems. If I hear these issues have been corrected, I'll try it again.