[Stable Update] 2021-08-27 - Kernels, Cutefish, NetworkManager, Gnome, Pamac, Mesa, Browsers, Xorg-Server, LibreOffice

[felix]

I also had the problem that LightDM failed during startup.
For me adding logind-check-graphical=true to the [LightDM] section in /etc/lightdm/lightdm.conf did the trick.