I solved it finally.
It was because of the corrupt indices remaining from upgrade of Kibana 7.17.7 to 8.5.3
Here it is defined in corrupt saved objects: resolve migration failures
I deleted the
.kibana_7
.kibana_task_manager_7
.kibana_event_log_7
but do not delete .security_7 because it deletes all built-in users.
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