This thread is such a massive failure of the community bug reporting process.

https://www.reddit.com/r/Fedora/comments/1s8jevj/a_message_to_fedora_devs_please_stop_interfering/

Apparently there's a small but significant fraction of users who see their browser home reset to the Fedora Home on Firefox updates or other circumstances... and they're all convinced this is some kind of evil intentional Fedora packaging feature that hijacks your preferences on every update, and that it must happen to everyone (it does not).

So far there is one known hypothesis for why this can happen (it involves Firefox Sync), but that doesn't cover all instances because some affected users claim not to use Sync. I reported this one upstream so hopefully there will be a solution soon. Nobody had until now...

Meanwhile, not a single affected user has bothered to write up reliable repro steps or follow through with maintainers on tracking down the root cause.

I've also looked at upstream bugs and found several shaped like "Firefox lost my prefs on upgrade", but none of them were followed through to a root cause either.

Of course, when Firefox loses the home page pref and it reverts to about:home, people shrug and set it back... but when Fedora Firefox does the same and it reverts to start.fedoraproject.org, it's clearly a Red Hat conspiracy to hijack people's browsers and they demand Fedora remove the default home page branding override entirely, instead of working with a developer to get the bug fixed...

@lina Well the branded homepage usually sucks, and getting homepage reset must be frustrating and annoying. Maybe learn from opensuse, who has branding-opensuse and branding-upstream, thus free from this issue.
@commdserv That's still just a workaround for the bug. There's no reason for the home page to be reset to begin with.
@lina True this is a workaround, but for now it might be needed to calm people down, so that actual troubleshooing may begin...
Due to the "persistent" nature, will btrfs snapshots on firefox folder work? By comparing changes between versions.

@commdserv Just anyone who consistently sees this issue on upgrades sharing their profile directory would be a good start to try to diagnose it... maybe even just the prefs.js file.

Ideally you want a profile dir snapshot prior to the first run with an upgraded version, along with the version known to trigger the reset on that profile.