The patch has been posted upstream and it seems to be fixing the problem already:
Moving to POST
I am just running into this with cockpit-appstream's gating test, it seems to reproduce this bug (through a PackageKit crash) every time on the OSCI infra (unfortunately not on my local 8.1 VM): https://dashboard.osci.redhat.com/#/artifact/brew-build/aid/22673078?focus=tc:osci.brew-build.tier0.functional
journal shows that assertion failure: https://jenkins.osci.redhat.com/job/rhel-8-pr-pipeline/3085/artifact/package-tests/cockpit-appstream/logs/verify/TestUpdates-testBasic-rhel-8-1-10.88.0.1-22-FAIL.log
This is from https://jenkins.osci.redhat.com/blue/organizations/jenkins/rhel-8-pr-pipeline/detail/rhel-8-pr-pipeline/3085/artifacts
So I'm happy to re-run this to validate a fix.
Or better yet, I think the original infra problem from your previous libdnf update got fixed (which hid the regression), so the next libdnf update should trigger cockpit-appstream automatically through reverse dependency testing.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.