Manjaro GNOME immediately logs out after logging in (via GUI)
EDIT: I kinda solved it by installing Wayland (with Nvidia card, Ouch!) to replace Xorg. Not sure if this is gonna last though. Perhaps Manjaro is the one I'm gonna throw out FIRST if anything happens from now on.
What should be the first line of defense? Timeshift?
This happened after I installed AUR package masterpdfeditor and 2 applications from github (some hashing algorithm programs, I think they were "Dilithium" and "Latice-based-cryptography-main", one of them was provided by NIST.)
If using GUI: I login, black screen for few seconds, then back at login screen.
If going to ctrl+alt+f2, login successful, then startx, see picture provided (higher quality).
I tried adding a new user, but result is the same.
I have a live usb to do the Timeshift. (I can also chroot if necessary... But I'm not extremely professional)
The problem is that you used Manjaro to begin with. The whole point of being on an arch based distro is to use the AUR. Manjaro tries to make arch more stable by holding back packages, but then because of that, if you install packages from the AUR (which again is the whole point of being on arch), you make Manjaro less stable than Arch itself. So it's a lose lose situation.
If you want to stick to Arch based, either go vanilla Arch or EndeavourOS. Or if you don't care about the AUR but still want updated packages, I can not recommend OpenSuse Tumbleweed enough.
Allrighty, let's try turning it into "helping". When one finds themselves using manjaro, they should:
Prepare a flash drive with recent arch iso flashed (that shouldn't be strictly necessary, but just in case);
Go to the pacman's mirrorlist and replace their repos with the proper ones (i.e. from arch);
Do a -Syyuu base --overwrite=*;
(optional) In case of trouble, boot to the drive flashed at step 0, make necessary mounts, arch-chroot, solve the problems. One can also try pacstrap-ing instead.
This is a rather high-level overview off the top of my head, and one would likely have to make a few tweaks here and there. Still, I hope it helps :)
What you described would ruin a perfectly good install. It's like installing Ubuntu then switching the repos to Debian and force overwriting installed files. Why not just install Debian (or Arch, in this case)?
I wonder how many people follow "well meaning" advice like this then blame Manjaro.
Well, that's kinda how I once converted my artix to arch (skipping a few f-ups on my part and the caveats of switching init), so I'm pretty sure it can work... Although I can try this in a VM if I have some spare time
It may work but there's no point in doing it. You get something that's neither proper Arch nor Manjaro.
Manjaro is built around a branch which doesn't exist in Arch, unlike other Arch derivates, and mixing the installed Manjaro packages with Arch packages can lead to unpredictable results.
That's why you change the repos, tho, instead of mixing those from arch and manjaro, and do overwrites to avoid trouble with their configs. Also, I have a feeling pacman tells you when a package managed by it is no longer in the repos, so you just remove it to not accidentally take part in another round of ddos-ing aur or whatever manjaro's packages currently do for fun.
As for why, that's just to avoid setting up everything from scratch