They removed privacy.resistFingerprinting.spoofOsInUserAgentHeader a while back as well. I find that suspicious.
This is kind of crazy since there are new fingerprinting techniques all the time and if they miss even one data point the whole game is lost. The smarter movie would be to make sure that fingerprints are unique/randomized so that even the same person looks like different people but for some reason they're confident they can account for every possible identifying metric 100% of the time.