Fedora 41 LXQt Spin with older AMD A10-7800 Radeon Graphics installed and worked well.
Fedora 42 LXQt Spin upgrade from FC41 resulted in unusable graphic display at login.
Fedora 42 LXQt Spin new install resulted in the same graphic display problem.
The display appeared smeared as if refresh sync rate was off: colors of the pretty FC 42 background (6x9=54 and the whale cloud) were smeared across the screen.
Problem was reproduced with either DVI or VGA monitor, which work well with FC41 LXQt.
Fedora 42 LXQt Spin new install on an AMD Ryzen 5 5600G with Radeon Graphics PC worked fine.
Fedora 42 Cinnamon and XFCE and LXDE new installs on AMD A10-7800 Radeon Graphics CPU worked fine.
Workaround:
(1): Reinstall Fedora 41 LXQt on AMD A10-7800 chip PC and defer FC42 upgrade.
(2): Edit /etc/sddm.conf in Fedora 41 LXQT
After:
DisplayServer=wayland
Insert:
DisplayServer=x11
(3) Use command-line to upgrade LXQt to Fedora 42 per: