Full traceback is:

unit-keystone-0: 09:50:46 DEBUG juju.worker.uniter.remotestate got leader settings change for keystone/0: ok=true
unit-keystone-0: 09:50:46 INFO unit.keystone/0.juju-log Bootstrapping keystone.
unit-keystone-0: 09:50:49 WARNING unit.keystone/0.config-changed /etc/keystone/fernet-keys/ does not contain keys, use keystone-manage fernet_setup to create Fernet keys.
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed Traceback (most recent call last):
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed   File "/var/lib/juju/agents/unit-keystone-0/charm/hooks/config-changed", line 937, in <module>
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed     main()
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed   File "/var/lib/juju/agents/unit-keystone-0/charm/hooks/config-changed", line 930, in main
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed     hooks.execute(sys.argv)
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed   File "/var/lib/juju/agents/unit-keystone-0/charm/charmhelpers/core/hookenv.py", line 963, in execute
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed     self._hooks[hook_name]()
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed   File "/var/lib/juju/agents/unit-keystone-0/charm/charmhelpers/contrib/openstack/utils.py", line 1900, in wrapped_f
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed     return restart_on_change_helper(
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed   File "/var/lib/juju/agents/unit-keystone-0/charm/charmhelpers/core/host.py", line 865, in restart_on_change_helper
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed     r = lambda_f()
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed   File "/var/lib/juju/agents/unit-keystone-0/charm/charmhelpers/contrib/openstack/utils.py", line 1901, in <lambda>
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed     (lambda: f(*args, **kwargs)),
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed   File "/var/lib/juju/agents/unit-keystone-0/charm/charmhelpers/contrib/hardening/harden.py", line 90, in _harden_inner2
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed     return f(*args, **kwargs)
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed   File "/var/lib/juju/agents/unit-keystone-0/charm/hooks/config-changed", line 235, in config_changed
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed     do_openstack_upgrade_reexec(configs=CONFIGS)
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed   File "/var/lib/juju/agents/unit-keystone-0/charm/hooks/keystone_utils.py", line 745, in do_openstack_upgrade_reexec
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed     do_openstack_upgrade(configs)
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed   File "/var/lib/juju/agents/unit-keystone-0/charm/hooks/keystone_utils.py", line 793, in do_openstack_upgrade
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed     bootstrap_keystone(configs=configs)
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed   File "/var/lib/juju/agents/unit-keystone-0/charm/hooks/keystone_utils.py", line 888, in bootstrap_keystone
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed     subprocess.check_call((
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed   File "/usr/lib/python3.10/subprocess.py", line 369, in check_call
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed     raise CalledProcessError(retcode, cmd)
unit-keystone-0: 09:50:50 WARNING unit.keystone/0.config-changed subprocess.CalledProcessError: Command '('keystone-manage', 'bootstrap', '--bootstrap-username', '_charm-keystone-admin', '--bootstrap-password', 'prpnqgbqfkj27xPV5r28hkFyxc63KkmVh9SjPs7H8wxg6PB9MTZWg2Hf8MYLJkBM', '--boot
strap-project-name', 'admin', '--bootstrap-role-name', 'Admin', '--bootstrap-service-name', 'keystone', '--bootstrap-admin-url', 'http://172.20.1.216:35357/v3', '--bootstrap-public-url', 'http://172.20.1.216:5000/v3', '--bootstrap-internal-url', 'http://172.20.1.216:5000/v3', '--bootst
rap-region-id', 'RegionOne')' returned non-zero exit status 1.
unit-keystone-0: 09:50:50 ERROR juju.worker.uniter.operation hook "config-changed" (via explicit, bespoke hook script) failed: exit status 1

Confirmed.