I have a PXC environment. When I try "ALTER TABLE" including "ADD UNIQUE" and table contains duplicate entries, the result is "Disconnected" node or even whole cluster crash.

Environment:
3 servers, Debian Linux 11
8.0.33-25.1 Percona XtraDB Cluster (GPL), Release rel25, Revision 0c56202, WSREP version 26.1.4.3
mysqld.cnf attached

MySQL table definition:
mysql> describe iot_devices_values;
+----------------+--------------+------+-----+-------------------+-------------------+
| Field          | Type         | Null | Key | Default           | Extra             |
+----------------+--------------+------+-----+-------------------+-------------------+
| id             | int unsigned | NO   | PRI | NULL              | auto_increment    |
| iot_devices_id | int unsigned | NO   | MUL | NULL              |                   |
| timestamp      | timestamp    | NO   |     | CURRENT_TIMESTAMP | DEFAULT_GENERATED |
| data           | json         | NO   |     | NULL              |                   |
+----------------+--------------+------+-----+-------------------+-------------------+
4 rows in set (0.00 sec)mysql> show indexes from iot_devices_values;
+--------------------+------------+----------------+--------------+----------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| Table              | Non_unique | Key_name       | Seq_in_index | Column_name    | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Visible | Expression |
+--------------------+------------+----------------+--------------+----------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| iot_devices_values |          0 | PRIMARY        |            1 | id             | A         |       32780 |     NULL |   NULL |      | BTREE      |         |               | YES     | NULL       |
| iot_devices_values |          1 | iot_devices_id |            1 | iot_devices_id | A         |           7 |     NULL |   NULL |      | BTREE      |         |               | YES     | NULL       |
+--------------------+------------+----------------+--------------+----------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
2 rows in set (0.01 sec)mysql>

Attempted command:
ALTER TABLE `iot_devices_values` ADD UNIQUE(`iot_devices_id`, `timestamp`);

Result (expected, I'm aware that the table contains duplicates):
ERROR 1062 (23000): Duplicate entry '43-2023-03-18 06:25:17' for key 'iot_devices_values.iot_devices_id_2'

Unexpected result:
One or multiple nodes in the PXC cluster become "Disconnected" and make the cluster broken. In my test scenario I broke server 2 (timestamp 2023-08-24T14:56:39).
mysql> show status like 'wsrep_clu%';
+----------------------------+--------------------------------------+
| Variable_name              | Value                                |
+----------------------------+--------------------------------------+
| wsrep_cluster_capabilities |                                      |
| wsrep_cluster_conf_id      | 18446744073709551615                 |
| wsrep_cluster_size         | 0                                    |
| wsrep_cluster_state_uuid   | 62cb5731-428a-11ee-8fd0-07da8bce8819 |
| wsrep_cluster_status       | Disconnected                         |
+----------------------------+--------------------------------------+
5 rows in set (0.00 sec)mysql>
{{{}{}}}I will attach error.log from all 3 nodes.

Thanks a lot!

Vítek