I think Firefox might actually enable this by default for third party sites, but not 100% what this about:config one does: privacy.trackingprotection.fingerp

I think Firefox might actually enable this by default for third party sites, but not 100% what this about:config one does: privacy.trackingprotection.fingerprinting.enabled This would make sense since messing with values for the root frame could cause unwanted side effects, but you're not likely to care if some iframe gets your screen resolution or CPU count wrong.