I stand corrected for me previous review: one website that was giving me the biggest of troubles was attempting to do its own dark-mode, saw this app working: and both doubled down and looped in itself, creating weird artifacts that (Well, I think I was seeing the matrix..).
Whitelisted the site, reset the website to use its own darkmode, and everything works great again.

One point I bring back from my previous 3-star review: "this extension is my go-to plugin for every system I use Firefox on". Really, I value a good dark filter over ad-blockers.