Xtrabackup Waiting for table backup lock mysql 8.0

MySQL & MariaDB Percona XtraBackup
1

We are running full backups on replica node.

At times we are seeing this in the processlist and backups is not moving and replication lag increases.
| 738 | system user | | DBX | Query | 19472 | Waiting for table backup lock | DROP TABLE DBX /* generated by server */ | 19471738 | 0 | 0 |

2 

+---------------+---------------+--------------+---------------------+-------------+-----------+----------------+-----------------------------------------------------+
| OBJECT_TYPE   | OBJECT_SCHEMA | OBJECT_NAME  | LOCK_TYPE           | LOCK_STATUS | THREAD_ID | PROCESSLIST_ID | PROCESSLIST_INFO                                    |
+---------------+---------------+--------------+---------------------+-------------+-----------+----------------+-----------------------------------------------------+
| BACKUP TABLES | NULL          | NULL         | SHARED              | GRANTED     |     50313 |          50268 | NULL                                                |
| GLOBAL        | NULL          | NULL         | INTENTION_EXCLUSIVE | GRANTED     |       783 |            738 | DROP TABLE `Y` /* generated by server */ |
| BACKUP LOCK   | NULL          | NULL         | INTENTION_EXCLUSIVE | GRANTED     |       783 |            738 | DROP TABLE `Y` /* generated by server */ |
| SCHEMA        | x          | NULL         | INTENTION_EXCLUSIVE | GRANTED     |       783 |            738 | DROP TABLE `Y` /* generated by server */ |
| TABLE         | x          | Y | EXCLUSIVE           | GRANTED     |       783 |            738 | DROP TABLE `Y` /* generated by server */ |
| BACKUP TABLES | NULL          | NULL         | INTENTION_EXCLUSIVE | PENDING     |       783 |            738 | DROP TABLE `Y` /* generated by server */ |
| TABLE         | fact          | Y | SHARED_HIGH_PRIO    | PENDING     |     57403 |          57360 | NULL                                                |
+---------------+---------------+--------------+---------------------+-------------+-----------+----------------+-----------------------------------------------------+

I wondering how backup tables and the DDL replicated from primary are under same thread.

3

Can you post the backup command that you are executing?
Xtrabackup 8.0 will by default use --lock-ddl
Here is more reference,