The issue seems caused by we did not have webhook to update the global clusterset, but relay on the reconciled to check the update back. so there have a time interval that the global clusterset will be use LegacyClusterSetLabel in a short time window.
Verified using 2.1.0-DOWNANDBACK-2022-08-11-23-42-45
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: Red Hat Advanced Cluster Management 2.6.0 security updates and bug fixes), 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/RHSA-2022:6370