Further data, the problems started in 3.2.6. The render group has been fixed in 3.2.7 but the reference to the kvm group remains:
--- eudev-3.2.6/rules/50-udev-default.rules 2018-02-20 12:36:19.000000000 +0000
+++ eudev-3.2.7/rules/50-udev-default.rules 2018-09-21 13:22:02.000000000 +0100
@@ -36,8 +36,8 @@
SUBSYSTEM=="media", GROUP="video"
SUBSYSTEM=="cec", GROUP="video"
-SUBSYSTEM=="drm", KERNEL=="renderD*", GROUP="render", MODE="@GROUP_RENDER_MODE@"
-SUBSYSTEM=="kfd", GROUP="render", MODE="@GROUP_RENDER_MODE@"
+SUBSYSTEM=="drm", KERNEL=="renderD*", GROUP="video", MODE="0666"
+SUBSYSTEM=="kfd", GROUP="video", MODE="0666"
SUBSYSTEM=="sound", GROUP="audio", \
OPTIONS+="static_node=snd/seq", OPTIONS+="static_node=snd/timer"
@@ -79,7 +79,7 @@
KERNEL=="fuse", MODE="0666", OPTIONS+="static_node=fuse"
# The static_node is required on s390x and ppc (they are using MODULE_ALIAS)
-KERNEL=="kvm", GROUP="kvm", MODE="@DEV_KVM_MODE@", OPTIONS+="static_node=kvm"
+KERNEL=="kvm", GROUP="kvm", MODE="0666", OPTIONS+="static_node=kvm"
SUBSYSTEM=="ptp", ATTR{clock_name}=="KVM virtual PTP", SYMLINK += "ptp_kvm"