Running the Enterprise plugin.
Kibana 7.11.2
Elasticsearch 7.11.2
RoR: 1.29.0
When opening a dashboard a call is made towards the default index pattern.
http://x.x.x.x:8001/api/index_patterns/_fields_for_wildcard?pattern=defaultindex-*&meta_fields=_source&meta_fields=_id&meta_fields=_type&meta_fields=_index&meta_fields=_score
However, not all users have access to this index.
A few milliseconds later, a second call is made for the index pattern relevant for the dashboard:
http://x.x.x.x:8001/api/index_patterns/_fields_for_wildcard?pattern=readonlyrest_audit-*&meta_fields=_source&meta_fields=_id&meta_fields=_type&meta_fields=_index&meta_fields=_score
This looks like a bug in Kibana itself, but double check with you.