Comment 4 for bug 1738581

The change there seems buggy to me, warnings are useful to us for debugging and usually don't contain private info (or are not more likely to contain info that errors logs).

One local example (xenial)

$ journalctl -b --priority=warning | grep -i org.freedesktop.Notifications

mars 15 16:10:03 ubuntudbg org.freedesktop.Notifications[3074]: **
(notify-osd:3450): WARNING **: stack_close_notification_handler():
notification id == 0, likely wrong

$ journalctl -b --priority=err | grep -i org.freedesktop.Notifications
$

Those sort of warning usually don't contain any sensitive info and are
very valuable in figuring issues

The bug there to me is that gdm is logging standard "stdout/info" messages and those are ending up in the systemd journal being considered as warnings. Those logs shouldn't be there in the first place or should be in a lower level, that's either a bug in the way gdm/gtk are logging output or in journald.