The actual issue is having ubi based on RHEL 8.3 while having CentOS 8.2 and *not* the updated ubi repo enabled.

An alternate solution, instead of pinning to 8.2 in the image would be to re-add the ubi repository config which is being removed at some point. I've done some tests with the 8.3 image and the ubi repo enabled and works fine.

# dnf install python3-oslo-context --nogpgcheck
Updating Subscription Management repositories.
Unable to read consumer identity

This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.

Last metadata expiration check: 0:03:33 ago on Thu Nov  5 15:11:44 2020.
Dependencies resolved.
==============================================================================================================================================================================================
 Package                                      Architecture                  Version                                                    Repository                                        Size
==============================================================================================================================================================================================
Installing:
 python3-oslo-context                         noarch                        3.1.1-0.20201019091913.57dbded.el8                         delorean-component-common                         25 k
Installing dependencies:
 git-core                                     x86_64                        2.27.0-1.el8                                               ubi-8-appstream                                  5.7 M
 less                                         x86_64                        530-1.el8                                                  BaseOS                                           164 k
 libedit                                      x86_64                        3.1-23.20170329cvs.el8                                     BaseOS                                           102 k
 openssh                                      x86_64                        8.0p1-5.el8                                                ubi-8-baseos                                     520 k
 openssh-clients                              x86_64                        8.0p1-5.el8                                                ubi-8-baseos                                     666 k
 python3-debtcollector                        noarch                        2.2.0-0.20201019081120.649189d.el8                         delorean-component-common                         31 k
 python3-funcsigs                             noarch                        1.0.2-17.el8                                               delorean-master-testing                           30 k
 python3-pbr                                  noarch                        5.4.3-2.el8                                                delorean-master-testing                           90 k
 python3-setuptools                           noarch                        50.3.0-1.el8                                               delorean-master-testing                          972 k
     replacing  platform-python-setuptools.noarch 39.2.0-6.el8
 python3-wrapt                                x86_64                        1.12.1-3.el8                                               delorean-master-testing                           55 k

Transaction Summary
==============================================================================================================================================================================================
Install  11 Packages

Total size: 8.3 M
...