Comment 27 for bug 1951491

Yes, based on your link this 'work around' disables new cgroups.
: "If for some reason you need to keep the legacy cgroup v1 hierarchy, you
can select it via a kernel parameter at boot time:
systemd.unified_cgroup_hierarchy=0"

however, it at least allows a working session.

on another point: this problem happens with xubuntu which does not use gdm3, it uses lightdm.
So what ever session start script is being missed by the standard startx scripts we are all using for our various remote connection tools, is not specific to gdm.