New Release: Tor Browser 8.5a1

What I'm seeing with this user agent issue is that Mac users seemed to be the ones that had the compatibility issues and Linux users want the user agent changed back. I'm on Linux, and I've never had any OS compatibility issues with a spoofed Windows UA (probably because Linux is better about interoperability and sticking to standards than any proprietary OS). And even if I did, I would investigate it myself, like most Linux users. The "User will get frustrated and immediately cease usage of the program upon encountering any issues" problem may apply to Mac users, but it doesn't apply to most Linux users (otherwise they wouldn't be using Linux).

There are no downsides to changing it back either; yes, maybe in some cases websites will still be able to detect that you're using Linux, but some won't and even when they do spoofing a Windows UA won't be an issue since every other Tor Browser installation would be doing it too. Meanwhile, as it stands now the anonymity set is split between Linux users not spoofing a Windows UA and the (I assume considerably large) number of Linux users choosing to spoof it (as Linux users tend to be on the tech-savvier side and thus I imagine would have no problem installing an extension). So the problem was made worse and not better by this change, while ignoring the fact that there never was a problem in no-JS contexts.

Overall this change is eroding the trust many of your users have in you to make the most sensible default decisions. And people not trusting Tor Browser and rolling their own to whatever degree is a much bigger threat to its design than whatever esoteric OS fingerprinting issues you're worried about invalidating UA spoofing (which, like I said before, makes no sense anyway as even if your real OS is detected, them knowing you have a spoofed UA means nothing if every other Tor Browser is spoofing it too, just as it was in 7.x), even ignoring the fact that it's just not an issue in most no-JS contexts.

As for me I now have an extension installed to spoof my UA. It's open source but is it trustworthy? Hopefully it is. I gladly uninstalled my last UA spoofing extension years ago and now it feels like a major regression that I feel that I have no choice but to install another one.

Just giving into Mozilla's decision making on this issue is a lame excuse too. Has the Tor Browser team forgotten how to code? What's the point of a browser fork if it's not actually, you know, forked?

Overall I'm just annoyed because the logic behind this decision is so transparently flawed and people trust you to make better decisions than this. People shouldn't have to be investing their time in explaining the obvious to you but apparently they do now. I'm sorry for being snippy but this is a major violation of your mission.

I was already annoyed with you constantly dumbing down things UX-wise for the benefit of people who can't be bothered to read a single full sentence about a system that they're expecting to protect their anonymity (which is pointless as they will invariably find some way to screw things up due to their lack of knowledge no matter how many "dangerous" options you remove), but when it's gotten to the point of actually sacrificing privacy/anonymity because some random bozos report "I can't use my google docs!" (which they're probably signed into with an entirely identifiable account) to you (or some other stupid BS about corporate apps that probably can't even be used anonymously no matter what anyway as they all ask for phone numbers) then it's gone too far.

Maybe you can release two versions of Tor Browser? One for people who know what they're doing, are willing to read, and understand that everything might not work automaticaly, and one that's just Firefox with a pretty shade of green paint over it (which is what Tor Browser is trending toward)? Either way you need to do something to fix this because if you don't, you will eventually end up with the situation I just stated as a de facto reality due to a fork, at which point you will split the anonymity set of Tor users further and lose control over what that new team does. You need to make the right decision now before it's too late.