The title say it all, guys. I’ve trying to search on the fix of my problem for the last 4 hours on Steam getting stuck on “Loading user data”. The problem started after I update my system today (I always update every 1 week). To anyone who experienced my problem and have a fix please let me know, guys!!!
I had that two weeks ago.
What are you using
Wayland or X11
KDE plasma / gnome or XFCE?
Try login in an alternative Desktop and displamamanger
Just in case you didn’t tried yep stop the steam process in your task manager and launch steam again, steam getting stuck like that did happen sometimes on windows.
X11 and i3wm. This the first time happened to me though
I’ve done more than that, sir. I did that and even reboot my system. Remove steam and reinstall it again, install flatpak version still nothing.
I remove my 2 factor authentication/Steam guard, remove Family PIN, didn’t use QR code and just type account username and password manually (and use QR code), delete cache, delete steam runtime.tar.zx, still nothing! 
I must admit I don’t know what’s causing this, the flatpak version not working too is the weirdest part, like qwert.zuiop suggested you can try using wayland just the time to launch steam, and alternatively try on another computer.
You should also try to launch steam through the command line, that way you will have more informations to work with, maybe the reason why it’s stuck is writted here.
If the problem started right after a system update you could try to load from a previous system snapshot.
Something I didn’t say, sir. Is it because of Mesa? Because before I update my system there’s few prompt on me choosing what should I do on mesa (Because I think there’s new update that ain’t compatible or something I forgot). But what I do is just choice 1 which said (as far as I remember) moving mesa from pakman to opensuse and I just choose 1 and even on mesalibg (?) until I got to an option saying 1 “remove steam (v) 10.0.0.98” (like that) and just choice 2 where it said keep steam and that’s it. The system upgrades.
There you have it, try to revert.
Nvidia, AMD or Intel?
Nvidia drive or OpenSource driver?
AMD CPU and AMD GPU, sir. And how to revert it back? Use snap?
You need to load from a previous system snapshot, to do so reboot your computer, on the first graphical menu you have a option to start from a previous snapshot.
Choose in the list one that is before your breaking update and start it, you will be able to use your computer and test if steam launch.
If it launch you can apply the rollback with ‘sudo snapper rollback’ and reboot, if it’s not launching you can try another snapshot.