.kibana index is not available for snapshot

I'm trying to implement Kibana dashboard snapshots. As far as I know, dashboards are saved in the .kibana* index. In my case, it is .kibana_8.13.4_001 since I am using Kibana version 8.13.4. I can see that index under Index Management, as shown in the image below:

However, on the snapshot settings page, when I have to select indices to snapshot, the .kibana_8.13.4_001 index is not suggested, only those visible in the image:

I've tried to add a custom index pattern .kibana*, but I only get a snapshot of the following four indices:

Could you please tell me what I am doing wrong? What is the correct approach for making backups of Kibana dashboards?