ls /var/lib/patchmanager/ausmt/patches
for each patch file check files it's patching
then search for packages using rpm -qf filename
and reinstall each found package by using pkcon install package

One more problem... Other patches I had no trouble with doing it like this:

With coderus' method reinstalled each package, then unapplied them from PatchManager and reapplied them.

But the "Upcoming events on lockscreen" patch was a trickier one. I tried unapplying it and PatchManager said "Failed to remove patch" and it stayed activated.

I then decided to remove it with "pkcon remove lockscreen-upcoming". Now PatchManager told me the patch is no longer available and removed it from its list. I then reinstalled it from warehouse. Now when I started PatchManager it showed this patch already applied, and I'm in the same sorry state that I can't unapply it so that I could reapply it.

remove folders from /var/lib/patchmanager/ausmt/patches

This was not enough for Upcoming Events on lockscreen patch, so to save time for others potentially battling with this (and for me to remember for next update) here's how I got it working:

First uninstall:

Edit file /var/lib/patchmanager/ausmt/packages and remove the line which references lockscreen-upcoming.

Remove all added QML files that have been installed when lockscreen-upcoming was applied:

Then you can install it again from Warehouse and activate successfully from PatchManager.

It's so bad when patches creating new files. this is not the thing patches should really do.

@coderus
but what about diff between file and /dev/null? Is it bad or not?

bad. you should package new files, not apply with patch.

Even if post/pre contains file-check and rm-command for this file?

yes. everything new should be packaged.

coderus is right, a patch creating a file is BAD.
I like the idea of diff with /dev/null though. Maybe even /dev/random