It does not affect the display of most sites. These two are the only examples so far.

You can check the default colors (back text on white background) and also make sure you allow pages to choose their own colors.

• Settings -> General: Fonts & Colors -> Colors: "Override the colors specified by the page with your selections above"

Try "Never" if the default "Only with High Contrast themes" isn't working.

You can select a theme that has dark text on the tabs (toolbars) if you currently use a theme with light text.

You can change this pref on the about:config page from 3 to 2 to revert to the Firefox 94 behavior regarding to prefer dark or light background for webpages.

• layout.css.prefers-color-scheme.content-override [dark:0, light:1, system:2, browser:3]

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox

Thank you so much for the answer, but none of the settings did anything to the aforementioned sites. I also tried changing (...)content-override to 1, and it worked on all the other pages I have open, but not those two. :P

I restarted FF in between.

The bigthink.com website has parts (.bg-black) that have a black background and light text, so that happens by design and in intentional. If you get the dark background, but not the light text then something seems to override the light text color.