KDE desktop blank, KDE corrupted?

UPDATE2 - Solved hanks to Fun-Vermicelli-9934 on Reddit! The issue was in my configs, so I moved mv ~/.config ~/.config.bak mv ~/.local/share ~/.local-share.bak mv ~/.cache ~/.cache.bak And rebooted.

UPDATE: on a new user the issue doesn’t exist. So I guess KDE reinstall would help on my user? How do to it safely and what will be lost?
Hello,

I updated my system and it broke KDE. I can log in as normal, the screen flashes a couple of times, and my usual things open - browser works, konsole, etc, but no dolphin, no taskbar, no desktop.

Whenever I try to open dolphin via console, it opens for a few seconds, then I get

 dolphin
kf.iconthemes: Icon theme "oxygen" not found.
kf.iconthemes: Icon theme "gnome" not found.
kf.iconthemes: Icon theme "oxygen" not found.
kf.iconthemes: Icon theme "gnome" not found.
kf.iconthemes: Icon theme "oxygen" not found.
kf.iconthemes: Icon theme "gnome" not found.
kf.iconthemes: Icon theme "oxygen" not found.
kf.iconthemes: Icon theme "gnome" not found.
kf.iconthemes: Icon theme "oxygen" not found.
kf.iconthemes: Icon theme "gnome" not found.
kf.iconthemes: Icon theme "oxygen" not found.
kf.iconthemes: Icon theme "gnome" not found.
fish: Job 1, 'dolphin' terminated by signal SIGSEGV (Address boundary error)

Journalctl shows messages about dbus broker, but I’m not sure which specific errors to look for:

dbus-broker-launch[707]: Activation request for 'org.freedesktop.home1' failed: The systemd unit 'dbus-org.freedesktop.home1.service' could not be found.
dbus-broker-launch[819]: Service file '/usr/share//dbus-1/services/org.kde.dolphin.FileManager1.service' is not named after the D-Bus name 'org.freedesktop.FileManager1'.
dbus-broker-launch[819]: Service file '/usr/share//dbus-1/services/org.kde.kscreen.service' is not named after the D-Bus name 'org.kde.KScreen'.

I assume the core of the issue is the dbus-broker and missing files/wrong filenames after some convention changed in the update, or rather that I had mixed something up before, but how do I fix it?
I attempted the fix from this superuser issue but it didn’t fix it for me and I don’t want to risk messing things up even more.

I tried wayland and x11, same issue, I tried reverting a snapshot, but the only one I have has the same issue and that operation almost gave me a heart attack.

Could I reinstall KDE plasma (and remove all user preferences which probably cause the issues) without touching any of my personal files?
Would this command achieve that, or do I have to rummage through some leftover files:
sudo pacman install --reinstall kde-plasma-desktop

Thank you!

Likely just the ~/.cache directory - this happened to a number of users with one of the recent updates.

Specifically, you just need to remove the ~/.cache/fontconfig/* .