With the direction FF is taking it's gonna be forks for now.

The only thing that held me back from using LibreWolf over Firefox was that it disabled (automatic) dark mode on websites. I understand this is part of the "resist fingerprinting" configuration. There's a workaround now ( https://bugzilla.mozilla.org/show_bug.cgi?id=1732114).

In about:config update these 3 preferences:

• privacy.resistFingerprinting = false
• privacy.fingerprintingProtection = true
• privacy.fingerprintingProtection.overrides = +AllTargets,-CSSPrefersColorScheme