@inconspicuous-lurker-99@boymilk.cafe @nelson@wetdry.world According to this, you can disable privacy.resistFingerprinting and use privacy.fingerprintingProtection instead, which has a privacy.fingerprintingProtection.overrides setting that you can change to "+AllTargets,-CSSPrefersColorScheme" to disable the forced light mode.
I'm not sure why they added a new setting instead of making resistFingerprinting overridable, or what exactly the differences are.