Strange dual monitor behavior, after last KDE update

I have a 2-monitor setup.

Main: Landscape 1440p, HDMI
Secondary: Portrait, 1080p, HDMI
Both connected to 5500XT (6900XT is passed through to VMs)

Until recently, (almost) everything worked correct. However, since last update (3 days ago), it is broken…

If I switch input to my primary (HDMI → DP, I have other devices connected), and then switch back to HDMI, it behaves like I disconnect the monitor and moves all windows to the secondary.
Same thing happens if the screen saver kicks in. Computer never goes to sleep, it just shuts down the output, so the monitors go to sleep.
The problem was somehow fixed, when I disabled KScreen2, but then, every time I login I have to setup my monitors again (default primary is the once I use as secondary, and also I have portrait orientation for my secondary and moved it a bit from default position).

Anybody knows if there is a way to fix this? It is very annoying, as I switch inputs very often…

Screen 0: minimum 320 x 200, current 3760 x 1920, maximum 16384 x 16384
DisplayPort-0 disconnected (normal left inverted right x axis y axis)
HDMI-A-0 connected primary 2560x1440+0+240 (normal left inverted right x axis y axis) 597mm x 336mm
   2560x1440     59.95*+
   1920x1200     59.95 
   1920x1080    119.98    99.93    60.00    50.00    59.94    24.00    23.98 
   1600x1200     59.95 
   1680x1050     59.88 
   1280x1024    143.86   119.96    75.02    60.02 
   1440x900      59.95 
   1280x800      59.95 
   1280x720      60.00    50.00    59.94 
   1024x768     143.93   119.99    75.03    60.00 
   800x600      119.97    75.00    60.32 
   720x576       50.00 
   720x480       60.00    59.94 
   640x480       75.00    60.00    59.94 
   720x400       70.08 
DVI-D-0 connected 1200x1920+2560+0 left (normal left inverted right x axis y axis) 519mm x 324mm
   1920x1200     59.95*+
   1920x1080     59.95 
   1600x1200     60.00 
   1680x1050     59.88 
   1280x1024     60.02 
   1440x900      59.95 
   1280x960      60.00 
   1280x800      59.95 
   1280x720      59.95 
   1024x768      60.00 
   800x600       60.32 
   640x480       59.94 
   720x400       70.08  
Operating System: Manjaro Linux
KDE Plasma Version: 5.24.2
KDE Frameworks Version: 5.91.0
Qt Version: 5.15.2
Kernel Version: 5.16.11-2-MANJARO (64-bit)
Graphics Platform: X11
Display adapter: Advanced Micro Devices, Inc. [AMD/ATI] Navi 14 [Radeon RX 5500/5500M / Pro 5500M] (rev c5)

inxi -F

  Host: wizzy-manjaro-pc Kernel: 5.10.102-1-MANJARO x86_64 bits: 64
    Desktop: KDE Plasma 5.24.2 Distro: Manjaro Linux
  Type: Desktop System: Gigabyte product: X570 AORUS MASTER v: -CF
    serial: <superuser required>
  Mobo: Gigabyte model: X570 AORUS MASTER v: x.x
    serial: <superuser required> UEFI: American Megatrends LLC. v: F33a
    date: 01/22/2021
  Info: 12-core model: AMD Ryzen 9 5900X bits: 64 type: MT MCP cache:
    L2: 6 MiB
  Speed (MHz): avg: 3106
    min/max: 2200/5994:6294:6442:6146:5846:5102:4950:5698:5550:5398:5250 cores:
    1: 2981 2: 3599 3: 2879 4: 2886 5: 2880 6: 2879 7: 3805 8: 3086 9: 2951
    10: 2975 11: 2947 12: 2951 13: 2879 14: 3599 15: 2878 16: 3582 17: 2880
    18: 2872 19: 3755 20: 3037 21: 2912 22: 2931 23: 3497 24: 2924
  Device-1: AMD Navi 21 [Radeon RX 6800/6800 XT / 6900 XT] driver: vfio-pci
    v: 0.2
  Device-2: AMD Navi 14 [Radeon RX 5500/5500M / Pro 5500M] driver: amdgpu
    v: kernel
  Device-3: Logitech HD Pro Webcam C920 type: USB
    driver: snd-usb-audio,uvcvideo
  Display: x11 server: X.Org v: driver: X: loaded: amdgpu,ati
    unloaded: modesetting,radeon gpu: amdgpu resolution: 1: 1200x1920~60Hz
    2: 2560x1440~60Hz
  OpenGL: renderer: AMD Radeon RX 5500 XT (NAVI14 DRM 3.40.0
    5.10.102-1-MANJARO LLVM 13.0.1)
    v: 4.6 Mesa 21.3.7
  Device-1: AMD Navi 21 HDMI Audio [Radeon RX 6800/6800 XT / 6900 XT]
    driver: vfio-pci
  Device-2: AMD Navi 10 HDMI Audio driver: snd_hda_intel
  Device-3: Creative Sound Blaster GC7 type: USB
    driver: cdc_acm,hid-generic,snd-usb-audio,usbhid
  Device-4: Logitech HD Pro Webcam C920 type: USB
    driver: snd-usb-audio,uvcvideo
  Sound Server-1: ALSA v: k5.10.102-1-MANJARO running: yes
  Sound Server-2: PipeWire v: 0.3.47 running: yes
  Device-1: Intel Wi-Fi 6 AX200 driver: iwlwifi
  IF: wlp6s0 state: down mac: 02:ed:0c:46:5e:2c
  Device-2: Intel I211 Gigabit Network driver: igb
  IF: enp7s0 state: up speed: 1000 Mbps duplex: full mac: b4:2e:99:f7:3e:40
  Device-3: Realtek RTL8125 2.5GbE driver: vfio-pci
  IF-ID-1: virbr0 state: up speed: 10 Mbps duplex: unknown
    mac: 52:54:00:44:1a:d2
  IF-ID-2: vnet0 state: unknown speed: 10 Mbps duplex: full
    mac: fe:54:00:6b:44:3a
  Device-1: Intel AX200 Bluetooth type: USB driver: btusb
  Report: rfkill ID: hci0 state: up address: see --recommends
  Local Storage: total: 5 TiB used: 1.21 TiB (24.3%)
  ID-1: /dev/nvme0n1 vendor: Samsung model: SSD 970 EVO 500GB
    size: 465.76 GiB
  ID-2: /dev/nvme2n1 vendor: Samsung model: SSD 970 EVO 250GB
    size: 232.89 GiB
  ID-3: /dev/sda vendor: Toshiba model: HDWE140 size: 3.64 TiB
  ID-4: /dev/sdb vendor: Samsung model: SSD 840 EVO 250GB size: 232.89 GiB
  ID-5: /dev/sdc vendor: Samsung model: SSD 850 EVO 500GB size: 465.76 GiB
  ID-1: / size: 448.43 GiB used: 194.68 GiB (43.4%) fs: ext4
    dev: /dev/nvme0n1p2
  ID-2: /boot/efi size: 299.4 MiB used: 288 KiB (0.1%) fs: vfat
    dev: /dev/nvme0n1p1
  ID-1: swap-1 type: partition size: 8.8 GiB used: 0 KiB (0.0%)
    dev: /dev/nvme0n1p3
  System Temperatures: cpu: 45.0 C mobo: 16.8 C gpu: amdgpu temp: 56.0 C
  Fan Speeds (RPM): N/A gpu: amdgpu fan: 993
  Processes: 508 Uptime: 1h 36m Memory: 62.74 GiB used: 39.15 GiB (62.4%)
  Shell: Zsh inxi: 3.3.13

This has been the case for me ever since I even installed the OS including KDE… just jot on input switch but when turning the monitor on. Turning off is fine, turning on “disconnects” it for a couple seconds.

I have no idea what causes it and at some point I just gave up looking.

But anyway, does a downgrade to the old version fix it for you? Might just be a bug in the latest version seeing as Arch doesn’t always ship actually tested versions.

Not sure how to downgrade the version. Is it only the KScreen2 i need to downgrade, or more things?

I don’t know how that works on Arch. On Fedora there’s a transaction history and they can be reverted individually. Not sure if Arch has anything similar or if you need to install older releases individually.

Well whatever was updated I’d say, otherwise you introduce more variables in the testing which won’t help you anything.