When using a distro that provides real changelogs for package updates (e.g. Ubuntu-based distros, openSUSE Leap, Fedora), you can see the changelogs for each package entry on Discover's updates page when doing online updates.
However when doing offline updates, Discover gathers all the package entries into one big one, and that one doesn't show any changelogs.
Clearly PackageKit has this data available; we just need to show it to the user when doing offline updates as well as online updates.
Created attachment 151132 [details]
Changelogs in DNF and Discover's online updates
Created attachment 151133 [details]
Changelogs in DNF but not Discover's offline updates
A possibly relevant merge request was started @ https://invent.kde.org/plasma/discover/-/merge_requests/351
Git commit 053387ec2bb9d1387f850f9434fd1515e3cb9e1e by Nate Graham, on behalf of Aleix Pol Gonzalez.
Committed on 03/11/2022 at 19:43.
Pushed by ngraham into branch 'master'.
pk: Improve information on offline updates
Show instead of showing it as changelog, offer an empty changelog and
instead expect users to use the "more info" button to see the
description with a list of all packages plus their respective
M +1 -1 libdiscover/backends/PackageKitBackend/AppPackageKitResource.cpp
M +5 -6 libdiscover/backends/PackageKitBackend/PackageKitResource.cpp
M +2 -1 libdiscover/backends/PackageKitBackend/PackageKitResource.h
M +17 -9 libdiscover/backends/PackageKitBackend/PackageKitUpdater.cpp