[Bug]: sddm crashes at login

[i9l12e5]

Kernel

6.19.5-3-cachyos

Desktop Environment / Window Manager

KDE Plasma

CPU

AMD Ryzen 5 5600X

GPU / Driver

AMD Radeon RX 570

Description

Updated latest packages and rebooted system, then sddm process crashes while dual display is used during login. Login credentials are valid, as they work in TTY.

Steps to Reproduce

1. Start system with two displays on (both in DP ports)
2. Input password and login
3. Wait for login manager to reappear
4. Shutdown one display
5. Login works normally

Expected Behavior

After login, it should display desktop.

Actual Behavior

After inputting password for my username at login screen both displays go dark and then only flashing underscore appears. Few seconds later it returns to login manager.

Logs / Error Messages

https://paste.cachyos.org/p/7464598

Additional Context

No response

[ptr1337]

It seems the amdgpu crashes.

Does downgrading to LTS kernel or the firmware downgrading helps?

[i9l12e5]

No change while using 6.18.15-3-cachyos-lts kernel

[ptr1337]

No change while using 6.18.15-3-cachyos-lts kernel

How about downgrading firmware?
sudo pacman -S downgrade
sudo downgrae linux-firmware-amdgpu

[i9l12e5]

No change while using 6.18.15-3-cachyos-lts kernel

How about downgrading firmware? sudo pacman -S downgrade sudo downgrae linux-firmware-amdgpu

No change, tested multiple firmwares down to 20250613