Username showed in Kibana is always 'user'

Search Guard
6

Hello.
Thanks for notification about deprecated proxycache.
I replaced it with proxy. Could you please clarify “for all config options”? I tried to replace searchguard.proxycache.* with searchguard.proxy.*, but Kibana failed because of validation of [searchguard].proxy failed.
Now I removed searchguard.proxycache.* params.
Kibana still shows “user” insead of “admin”
The _searchguard/authinfo request returns:

{
  "user" : "User [name=admin, backend_roles=[offline_access, admin, uma_authorization, user], requestedTenant=null]",
  "user_name" : "admin",
      ...

Regarding source code noticed by @srgbnd in created issue. Seems username should be provided with restapiinfo.user_name. I see browser log and /kibana/api/v1 requests failed:

{"statusCode":500,"error":"Internal Server Error","message":"security_exception","attributes":{"body":{"error":{"root_cause":[{"type":"security_exception","reason":"Unexpected exception indices:data/read/get"}],"type":"security_exception","reason":"Unexpected exception indices:data/read/get"},"status":500}}}`

In case of I request only /api/v1/restapiinfo, there are logs in elasticsearch:

│ elasticsearch {"type": "server", "timestamp": "2021-03-31T11:40:40,057Z", "level": "ERROR", "component": "c.f.s.f.SearchGuardFilter", "cluster.name": "elasticsearch", "node.name": "kublr-logging-elasticsearch-client-84b4 │
│ 9f5c8b-759nr", "message": "Unexpected exception [_searchguard] InvalidIndexNameException[Invalid index name [_searchguard], must not start with '_'.]", "cluster.uuid": "4_5qVLmuSzirXadBLEOP1g", "node.id": "jn1rwlxfSt2WLg │
│ AbZ3bIzg" ,                                                                                                                                                                                                                  │
...
│ elasticsearch {"type": "server", "timestamp": "2021-03-31T11:40:40,062Z", "level": "WARN", "component": "r.suppressed", "cluster.name": "elasticsearch", "node.name": "kublr-logging-elasticsearch-client-84b49f5c8b-759nr", │
│  "message": "path: /_searchguard/api/permissionsinfo, params: {index=_searchguard, id=permissionsinfo, type=api}", "cluster.uuid": "4_5qVLmuSzirXadBLEOP1g", "node.id": "jn1rwlxfSt2WLgAbZ3bIzg" ,                           │
│ elasticsearch "stacktrace": ["org.elasticsearch.ElasticsearchSecurityException: Unexpected exception indices:data/read/get",                                                                                                 │
│ elasticsearch "at com.floragunn.searchguard.filter.SearchGuardFilter.apply0(SearchGuardFilter.java:323) [search-guard-suite-security-7.10.2-49.0.0.jar:7.10.2-49.0.0]",                                                      │

I already reported it here: Invalid index name [_searchguard], must not start with '_'.]
Perhaps these problems are related to each other