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)
But nobody checks that the package "compiles and works on Arch". It's not a prerequisite for putting things on AUR. The fact is that any AUR package, on any distro including Arch, may be just plain broken at any given time.
Even if the maintainer has successfuly built and ran the package it may be due to a particular circumstance specific to their system. There's no guarantee that they did it on a reference Arch system. There's no guarantee they did it on Arch. There's no guarantee they did it at all. Even if they did, any similarity to your current system may be purely coincidental.
Running a non-Arch distro may increase the odds of something going wrong. But maybe it decreases them. Short of testing all 87k AUR packages how can you tell? You've run into trouble with one package. I haven't run into trouble with 75 packages. If my experience is not statistically significant than how's yours, at one less order of magnitude?
Don't you think it's disingenuous to present this as if it were a constant, pressing issue with Manjaro?
I've actually never run into any issues on Arch. ◉‿◉
Like I said, I read the PKGBUILDS.
Everything single one I've ever installed, which is several hundred.
No amount of reading PKGBUILDs is going to save you from that one package that's incompatible with Manjaro package base flags and configuration. It's just not something immediately apparent.
Infact, the only AUR related thing I've ever had problems with is pamac. Why? Well, clearly it's not meant for Arch; no amount of recompiling pamac made it work any better.
Also, you kinda need an Arch derivative at the least to sign up to the AUR because of the ever changing verification they have. There's literally a command that you have to run that spits out the correct answer only if you're using Arch or a derivative.
What's funny is Manjaro is the only derivate that often fails the check because of the packages being behind.