Oracle database 12.2.0.1.0 - how can unavailable backup pieces be deleted

Hallo Community

• first

My query is:

select decode (STATUS,'A','Available','D', 'Deleted','U','Unavailable','X' , 'Expired' ) arc_status, count(*) from V$BACKUP_PIECE group by status

ARC_STATUS  COUNT(*)

----------- ----------

Unavailable     84

Deleted      1985

Available     1103

After

crosscheck backup;

delete noprompt expired backup;

delete noprompt obsolete recovery window of 35 days;

nothing changes

My question, where do unavailable backup pieces come from and how can I clean them up?

We use Oracle Release 12.2.0.1.0, RMAN catalog and Commvault Backup.

In the Commvault solution we use the following customized rman script

...

crosscheck backup;

delete noprompt expired backup;

...

• second

The same query - an other database