Only using uBlockOrigin and Privacy badger.
uBlock is certainly a great privacy tool and a great security one, too. IDK how much you need Privacy Badger though. Anyway...
I suggest you uninstall uBlock and Privacy Badger and replace them with NoScript. It has come a long way and is a great tool. It does not have the granular control of uBlock, but that's a good thing since it is easy to make the odd derp on uBlock due to the UI. I've accidentally clicked a wrong setting while trying to click another a few times. Also worth noting is uBlock's development has been somewhat erratic and for a while years ago was frozen long enough to make it obsolete (why I changed).
I'm not sure it is uBlock kicking you out, however. Not unless there's a few settings mangled.
I've never used Privacy Badger, but when it launched and they were punting it out, that gave me a fair idea. The biggest problem is that it's too simple. I would tentatively say that PB may be detecting some of the forum software as trackers since the forum is actually riddled with adds (I had no idea until actually visiting with my second user that only has vanilla settings and no browser addons). My guess is PB is killing persistent data associated with linux.org, too.
So, I suggest maybe save/export your data that you wanna keep (sessions, bookmarks, passwords, etc.) and then uninstall FF, purge the relevant folders (the entire $HOME/.mozilla can be killed if you only use FF and no other Mozilla stuffs). Then fresh install and start with NoScript. It still protects against cross-site tracking/scripting, js, persistent trackers and such. The only disadvantage is lack of granular control over specific elements (i.e. you block things by domain only). With NoScript, in Private Browsing, and with necessary settings, you'll find that most of your online identity is secured. If ya need a little extra, then add a per-launch randomly generated --height and --width value to your FF launcher (and don't maximize on everyday sites) use dedicated browsers for each function/area of your internet (TorBB for xhamster, naturally), and, if you're really paranoid, create a/some fake user(s) to run your browsers as. Of course if you have a static IP, you'll need a VPN. Luckily mine is dynamic so rebooting the router gives me a fresh start. And if you really hate YT tracking you, use youtube-dl and MPV to watch videos off-site.
Hope that smoothes your experience over. I can't see any other cause since this forum's software is quite widely used (at least I've seen many sites use it).