Since about a week or so, my PC literally takes 3-5 minutes to shut down. I see the spinning circle for like forever after KDE is gone.
Could someone guide me how to investigate and mitigate this issue?
PS: I’m at work today so I can’t answer before tonight.
Take a look with journalctl (read manual or alternatively use qjournalctl GUI) if there are some hints of what is going on. You can examine the previous bootlogs.
My advice: Get rid of KDE. It`such a freedom without.
I’ve been using KDE/Plasma literally for decades (first one was version 2, if memory does not fail me). The only tricky version was version 4. Version 5 and 6 are much more light-weight and rock solid, as long as one does not totally screws it up E.g. installing all sorts of themes (esp. SDDM, grub, etc) from various sources or one does not fiddle with inner core stuff without knowing what one does. I still install it as a fallback DE.
Guys, this is all too weird. After I wrote the OP, the system started to behave normally and shuts down in a few seconds 
I swear I waited at least 3 days before posting and the system fixed itself as if it had read my post 
Thanks for listening in, I guess.
Regarding KDE: I kinda like it so far (especially the wobbly windows effect 
). What freedoms might I be missing?
Maybe an update solved the issue.
While poking around with journalctl, I realized it only goes back 2 days. It took me a while to figure out this is because the file /usr/lib/systemd/journald.conf.d/00-journal-size.conf restricts it to 50M:
[Journal]
SystemMaxUse=50M
How did usr/lib/systemd/journald.conf.d/00-journal-size.conf get there? I’m pretty sure I never created it. The file is from the same day as the first entry in journalctl, but 1 hour “younger”. I’m confused.
Its probably from cachyos-settings as that package provides just such a file.
PS.
While I dont have that file so I looked using
sudo pacman -Fyx /usr/lib/systemd/journald.conf.d/00-journal-size.conf
But you can check local files by using, ex;
pacman -Qo /usr/lib/systemd/journald.conf.d/00-journal-size.conf
Thanks! I keep forgetting that pacman is able to show me all of this info and more. With Cachy on my PC and Ubuntu on my laptop, it’s all a bit much atm 
I’m still a neophyte coming from the dark side, y’know.
I somewhat suspected Cachy having its fingers in the game and yes, cachy-settings was updated lately. So now I wonder whether it is normal for 50M of journal to reach back only two days? I see tons of these messages spamming the journal
Sep 22 18:57:21 MasterComputer kernel: usb 1-9.4: reset high-speed USB device number 9 using xhci_hcd
Sep 22 18:57:22 MasterComputer kernel: usb 1-9.4: reset high-speed USB device number 9 using xhci_hcd
Sep 22 18:57:22 MasterComputer kernel: usb 1-9.4: reset high-speed USB device number 9 using xhci_hcd
Sep 22 18:57:24 MasterComputer kernel: usb 1-9.4: reset high-speed USB device number 9 using xhci_hcd
Sep 22 18:57:24 MasterComputer kernel: usb 1-9.4: reset high-speed USB device number 9 using xhci_hcd
Sep 22 18:57:25 MasterComputer kernel: usb 1-9.4: reset high-speed USB device number 9 using xhci_hcd
Sep 22 18:57:25 MasterComputer kernel: usb 1-9.4: reset high-speed USB device number 9 using xhci_hcd
Sep 22 18:57:26 MasterComputer kernel: usb 1-9.4: reset high-speed USB device number 9 using xhci_hcd
Sep 22 18:57:26 MasterComputer kernel: usb 1-9.4: reset high-speed USB device number 9 using xhci_hcd
Sep 22 18:57:28 MasterComputer kernel: usb 1-9.4: reset high-speed USB device number 9 using xhci_hcd
Sep 22 18:57:28 MasterComputer kernel: usb 1-9.4: reset high-speed USB device number 9 using xhci_hcd
Sep 22 18:57:29 MasterComputer kernel: usb 1-9.4: reset high-speed USB device number 9 using xhci_hcd
Sounds like my gaming mouse maybe?
I use my own /etc/systemd/journald.conf.d/00-journal-size.conf that only has
[Journal]
SystemMaxUse=50M
in it and my journal seems to go back about a week.
The journal might be larger (per-day) given certain activity or .. many errors or ‘spam’ as you mention.
Possibly related to a peripheral like a webcam or something?
I actually do have a Logitech Webcam, but it’s not connected. I suspect the G PRO mouse. Will dig into that another day 
for now, I cranked the limit up to 500M (maybe I’ll live to see the day when btrfs-assistant stops being smug about me having overbought )