Starting gdm.service may hang for 10 seconds

I have installed manjaro architect with gnome desktop on a virtual machine (Hyper-V). When I boot this machine the gdm.service takes a bit more than 10 seconds to start (until the login screen is shown).
The issue was difficult to analyze. The logs that I looked at did not show anything interesting.
The delay is caused by this setting in the gdm.service

In the virtual machine I use xf86-video-fbdev. gdm-wait-for-drm will always wait for 10 seconds in that case. systemd-analyze blame shows
10.568s gdm.service

I added a override config for gdm.service

Then the delay is gone, systemd-analyze blame shows
9ms gdm.service