Do not show the option to delete temporary files if systemd is running.
I was told on irc that gnome-3.36 leaves this up to systemd if systemd is running. Please don't show that option in gnome-control-center if systemd is running. Also if gnome is setting "purge after 30 days" but systemd is using 10d for /tmp/ and 30d for /var/tmp/, this creates confusion.