Comment 46 for bug 2011806

@Jonas: If KDE is launching apps in the same way gnome-shell was, it is inherently racy. It needs to make sure the child process is in the new cgroup before executing the application.

Doing the cgroup move after the app is already running causes problems if the application itself wants to configure cgroups, and could let child processes of the app itself escape the cgroup if they are created before the launcher tries to move the app.