[Thunderbird] Does mail.dark-reader.enabled have dependencies?

[NewKidOnTheBlock]

Today I noted that Thunderbird's native dark reader feature for emails isn't working.
After comparing to a fresh profile, I learned that it must be due to some of my about:config tweaks, because in vanilla Thunderbird, dark reader mode works just fine.
Do you have any idea what might cause dark reader to stop working?

The toggle is -> mail.dark-reader.enabled
Is there any way to check for its dependencies in about:config?
I've also applied some Betterfox tweaks - could it be some security-related parameter?

[NewKidOnTheBlock]

Found it!
It was privacy.resistFingerprinting
I had it set to true, because it worked really well in Thunderbird.