I've been using Linux for the better part of 4 years so I'm not new to it, but I've always learned stuff on an as-needed basis. Today I ran into an issue that I want to prevent in the future since I had a mini heart attack thinking about how my last backup on this system was... Never since I'm an idiot who forgot to set it up like I have on my laptop. Here are my steps:

• Ran sudo pacman -Syu; sudo pacman -Syy like I do every few days
• packages updated
• restarted computer
• can only boot into emergency mode

The journal was really long so I moved past it and went to the pacman logs, linux had updated from 6.4.3.1-1 to 6.4.3.1-2. Nothing else was important enough to cause the system to only boot into emergency (gcc, vbox, some libs) so I did a quick pacman -U to the cached 6.4.3.1-1 version for both Linux and Linux headers and rebooted - hurrah it was fixed! But I have no idea why it happened, or how to prevent it.

Has anyone else ran into this issue when updating? Any advice for preventing future crashes or issues like this so I don't fear updating?

Edit: Thanks to everyone for your advice! I ended up following multiple bits of advice. I reinstalled arch to get btrfs as the filesystem (didn't have anything important other than some docked-compose files and books yet) and grabbed the linux-lts kernal as a backup as well. I haven't configured snapper yet, but it's on my list of things to do.