The Alertmanager UI is still accessible via its route, but all necessary information should be available through the Console admin UI.
tested with 4.8.0-0.nightly-2021-05-19-123944, "Alertmanager UI" link is removed from Console Monitoring > Alerting page
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 (Moderate: OpenShift Container Platform 4.8.2 bug fix and security 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.