Please read this about how to format.
I updated your posts but next time please format your code.
.kibana-observability-ai-assistant-ilm-policy-conversations ILM policy seems to be the policy which removed:
[2023-11-07T02:49:38,057][INFO ][o.e.c.m.MetadataDeleteIndexService] [ServerName1] [.kibana-observability-ai-assistant-conversations-000001/5XHP_QxAS-64BYoV2LzJ4Q] deleting index
[2023-11-07T02:49:38,750][INFO ][o.e.c.m.MetadataDeleteIndexService] [ServerName1] [.kibana-observability-ai-assistant-kb-000001/F6B2OO7mQOuWbMMQCUi6nQ] deleting index
For those 3 ones, I don't know:
[2023-11-07T02:49:39,566][INFO ][o.e.c.m.MetadataDeleteIndexService] [ServerName1] [testingindex1/6m1nPxl-Sua1XeK3LZDNnw] deleting index
[2023-11-07T02:49:41,326][INFO ][o.e.c.m.MetadataDeleteIndexService] [ServerName1] [testingindex2/LgaVHLSjTMSwIGFxVDADng] deleting index
[2023-11-07T02:49:42,202][INFO ][o.e.c.m.MetadataDeleteIndexService] [ServerName1] [testingindex3/AiCid0NGSbS6DGDGof8NfA] deleting index
May be it's "a bug" and you should anyway upgrade to 8.10.4 or 8.11.0.
Or may be someone connected to your cluster did remove those testingindex* indices?