In case of a downgrade from 4.6, CAO needs to set its operator's status.managingOAuthAPIServer field to false to properly manage the OAuth API handover from the OAuth API server back to the OpenShift API server.
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 (OpenShift Container Platform 4.5.9 bug fix update), and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHBA-2020:3618