When gnome-software/packagekitd prepared packages for offline updates there was a checkbox in the shutdown dialog to perform offline updates before shutdown/reboot.
It was a convenient way for users to do updates and a reminder they have updates waiting without which many users fail to ever install updates.
Since (probably) F31 it no longer works. The checkbox doesn't show up when there are updates. To make the checkbox appear you have to open GNOME Software, go to the Updates screen, click "Reboot and install", click Cancel and then open the shutdown dialog.
This is most likely caused by suspending the packagekitd process. GNOME Shell then cannot check the status of updates and can't show the checkbox.
1) revert the change to suspend the packagekitd process when it's not needed.
2) resume the packagekitd process to get the updates status before the shutdown dialog is shown.
The option 2) would be preferred if it significantly doesn't delay the shutdown dialog because 1) would result in constantly higher consumption of memory.
Deferring a decision on Prioritized Bug status until after we consult with the Workstation WG. https://meetbot.fedoraproject.org/fedora-meeting/2020-02-26/fedora_prioritized_bugs_and_issues.2020-02-26-16.00.log.html#l-105
Workstation WG ticket created: https://pagure.io/fedora-workstation/issue/133
We think it's been broken since Fedora 29.
This is accepted as a Priortized Bug: https://meetbot.fedoraproject.org/fedora-meeting/2020-03-11/fedora_prioritized_bugs_and_issues.2020-03-11-15.00.log.html#l-73
BTW: this regressed in PackageKit 1.1.11 (nice version number). So Fedora 29 was indeed the first broken version.
Fixed in 3.36.1.