yum または dnf update を実行しても、新しいパッケージを利用できない

Issue

• システムを更新しようとすると、新しい RPM (新しいカーネルなど) が利用できないように見えます。

  # yum list kernel --showduplicates -v
  Loaded plugins: builddep, changelog, config-manager, copr, debug, debuginfo-install, download,         generate_completion_cache, groups-manager, kpatch, needs-restarting, playground, product-id, repoclosure, repodiff, repograph, repomanage, reposync, subscription-manager, uploadprofile
  Updating Subscription Management repositories.
  [..]
  YUM version: 4.7.0
  cachedir: /var/cache/dnf
  User-Agent: constructed: 'libdnf (Red Hat Enterprise Linux 8.4; generic; Linux.x86_64)'
  repo: downloading from remote: BaseOS
  rhel-8-for-x86_64-baseos-rpms                                                                                                     
  72 MB/s |  45 MB     00:00
  BaseOS: using metadata from Wed 16 Mar 2022 04:34:25 PM CET.
  repo: downloading from remote: AppStream
  rhel-8-for-x86_64-appstream-rpms                                                                                                                  
  69 MB/s |  39 MB     00:00
  AppStream: using metadata from Mon 21 Mar 2022 03:28:21 PM CET.
  Last metadata expiration check: 0:00:08 ago on Wed 23 Mar 2022 12:20:05 PM CET.
  Completion plugin: Generating completion cache...
  Installed Packages
  kernel.x86_64                                                                 4.18.0-305.10.2.el8_4                                                                 @baseos
  kernel.x86_64                                                                 4.18.0-348.20.1.el8_5                                                                 @@commandline
  Available Packages
  kernel.x86_64                                                                 4.18.0-305.el8                                                                        BaseOS