It seems that the password is displayed every time the driver tries to attach or detach a volume.

The following logs are display when executing an image to volume operation:
openstack volume create --size 32 --type powerflex --image cirros-0.5.2-x86_64-disk volpflex

When attaching!
Jan 25 10:32:26 zed-devstask cinder-volume[45668]: INFO cinder.volume.drivers.dell_emc.powerflex.driver [None req-bc7b1480-5cae-4fa3-b451-c2a36a79e285 admin None] Call os-brick to attach PowerFlex volume.
Jan 25 10:32:26 zed-devstask cinder-volume[45668]: DEBUG cinder.volume.drivers.dell_emc.powerflex.utils [None req-bc7b1480-5cae-4fa3-b451-c2a36a79e285 admin None] Converted id 2d59df0e-2ebc-4868-ab74-c9aa91a66fdf to PowerFlex OS name LVnfDi68SGirdMmqkaZv3w==. {{(pid=45668) id_to_base64 /opt/stack/cinder/cinder/volume/drivers/dell_emc/powerflex/utils.py:45}}
Jan 25 10:32:26 zed-devstask cinder-volume[45668]: DEBUG os_brick.initiator.connectors.scaleio [None req-bc7b1480-5cae-4fa3-b451-c2a36a79e285 admin None] ==> connect_volume: call "{'self': <os_brick.initiator.connectors.scaleio.ScaleIOConnector object at 0x7fc4e784b160>, 'connection_properties': {'scaleIO_volname': 'LVnfDi68SGirdMmqkaZv3w==', 'hostIP': None, 'serverIP': '10.225.108.171', 'serverPort': 443, 'serverUsername': 'admin', 'iopsLimit': None, 'bandwidthLimit': None, 'scaleIO_volume_id': '5aafd80d00000004', 'config_group': 'powerflex', 'failed_over': False, 'verify_certificate': False, 'certificate_path': None}}" {{(pid=45668) trace_logging_wrapper /usr/local/lib/python3.8/dist-packages/os_brick/utils.py:174}}
Jan 25 10:32:26 zed-devstask cinder-volume[45668]: DEBUG os_brick.initiator.connectors.base [None req-bc7b1480-5cae-4fa3-b451-c2a36a79e285 admin None] Acquiring lock "scaleio" by "os_brick.initiator.connectors.scaleio.ScaleIOConnector.connect_volume" {{(pid=45668) inner /usr/local/lib/python3.8/dist-packages/os_brick/initiator/connectors/base.py:68}}
Jan 25 10:32:26 zed-devstask cinder-volume[45668]: DEBUG os_brick.initiator.connectors.base [None req-bc7b1480-5cae-4fa3-b451-c2a36a79e285 admin None] Lock "scaleio" acquired by "os_brick.initiator.connectors.scaleio.ScaleIOConnector.connect_volume" :: waited 0.001s {{(pid=45668) inner /usr/local/lib/python3.8/dist-packages/os_brick/initiator/connectors/base.py:73}}
Jan 25 10:32:26 zed-devstask cinder-volume[45668]: INFO os_brick.initiator.connectors.scaleio [None req-bc7b1480-5cae-4fa3-b451-c2a36a79e285 admin None] Get ScaleIO connector password from configuration file
Jan 25 10:32:26 zed-devstask cinder-volume[45668]: DEBUG oslo.privsep.daemon [-] privsep: reply[7f6c8418-69aa-46d4-8595-4f9e02109658]: (4, 'Password123!') {{(pid=46568) _call_back /usr/local/lib/python3.8/dist-packages/oslo_privsep/daemon.py:501}}

When detaching:

Jan 25 10:32:39 zed-devstask cinder-volume[45668]: INFO cinder.volume.drivers.dell_emc.powerflex.driver [None req-bc7b1480-5cae-4fa3-b451-c2a36a79e285 admin None] Call os-brick to detach PowerFlex volume.
Jan 25 10:32:39 zed-devstask cinder-volume[45668]: DEBUG cinder.volume.drivers.dell_emc.powerflex.utils [None req-bc7b1480-5cae-4fa3-b451-c2a36a79e285 admin None] Converted id 2d59df0e-2ebc-4868-ab74-c9aa91a66fdf to PowerFlex OS name LVnfDi68SGirdMmqkaZv3w==. {{(pid=45668) id_to_base64 /opt/stack/cinder/cinder/volume/drivers/dell_emc/powerflex/utils.py:45}}
Jan 25 10:32:39 zed-devstask cinder-volume[45668]: DEBUG os_brick.initiator.connectors.scaleio [None req-bc7b1480-5cae-4fa3-b451-c2a36a79e285 admin None] ==> disconnect_volume: call "{'args': (<os_brick.initiator.connectors.scaleio.ScaleIOConnector object at 0x7fc4e784b160>, {'scaleIO_volname': 'LVnfDi68SGirdMmqkaZv3w==', 'hostIP': None, 'serverIP': '10.225.108.171', 'serverPort': 443, 'serverUsername': 'admin', 'iopsLimit': None, 'bandwidthLimit': None, 'scaleIO_volume_id': '5aafd80d00000004', 'config_group': 'powerflex', 'failed_over': False, 'verify_certificate': False, 'certificate_path': None}, Volume(_name_id=None,admin_metadata={},allocated_size=32,attach_status='detached',availability_zone='nova',bootable=False,cluster=<?>,cluster_name=None,consistencygroup=<?>,consistencygroup_id=None,created_at=2023-01-25T10:32:24Z,deleted=False,deleted_at=None,display_description=None,display_name='volpflex',ec2_id=None,encryption_key_id=None,glance_metadata=<?>,group=<?>,group_id=None,host='zed-devstask@powerflex#Env5_PD_Primary:Env5_SP_Primary',id=2d59df0e-2ebc-4868-ab74-c9aa91a66fdf,launched_at=None,metadata={},migration_status=None,multiattach=False,previous_status=None,project_id='21f5307fd4b548dc8fdba5a9df421edb',provider_auth=None,provider_geometry=None,provider_id='5aafd80d00000004',provider_location=None,replication_driver_data=None,replication_extended_status=None,replication_status='disabled',scheduled_at=2023-01-25T10:32:24Z,service_uuid=None,shared_targets=True,size=8,snapshot_id=None,snapshots=<?>,source_volid=None,status='downloading',terminated_at=None,updated_at=2023-01-25T10:32:24Z,use_quota=True,user_id='9435e8b82f4d4c258f2eac7c16c7de39',volume_attachment=VolumeAttachmentList,volume_type=VolumeType(a44e7498-3c87-418f-bf1e-246c92de6fe9),volume_type_id=a44e7498-3c87-418f-bf1e-246c92de6fe9)), 'kwargs': {}}" {{(pid=45668) trace_logging_wrapper /usr/local/lib/python3.8/dist-packages/os_brick/utils.py:174}}
Jan 25 10:32:39 zed-devstask cinder-volume[45668]: DEBUG os_brick.initiator.connectors.base [None req-bc7b1480-5cae-4fa3-b451-c2a36a79e285 admin None] Acquiring lock "scaleio" by "os_brick.initiator.connectors.scaleio.ScaleIOConnector.disconnect_volume" {{(pid=45668) inner /usr/local/lib/python3.8/dist-packages/os_brick/initiator/connectors/base.py:68}}
Jan 25 10:32:39 zed-devstask cinder-volume[45668]: DEBUG os_brick.initiator.connectors.base [None req-bc7b1480-5cae-4fa3-b451-c2a36a79e285 admin None] Lock "scaleio" acquired by "os_brick.initiator.connectors.scaleio.ScaleIOConnector.disconnect_volume" :: waited 0.001s {{(pid=45668) inner /usr/local/lib/python3.8/dist-packages/os_brick/initiator/connectors/base.py:73}}
Jan 25 10:32:39 zed-devstask cinder-volume[45668]: INFO os_brick.initiator.connectors.scaleio [None req-bc7b1480-5cae-4fa3-b451-c2a36a79e285 admin None] Get ScaleIO connector password from configuration file
Jan 25 10:32:39 zed-devstask cinder-volume[45668]: DEBUG oslo.privsep.daemon [-] privsep: reply[1b060a9d-d1d5-449f-a742-a2c9b5a29d4b]: (4, 'Password123!') {{(pid=46568) _call_back /usr/local/lib/python3.8/dist-packages/oslo_privsep/daemon.py:501}}