Got response code '400' contacting Elasticsearch

Using local instance of Logstash 7.10. with output to Cloud services made an horror hours to me as it is 'pretty bad not telling a thing' issue, however:
If your Logstash starts properly and connects to a cloud;
If yout Logstash doesn't send any data to Elastic
If your Logstash runs without any error, with only one repeating "WARNING";

[2020-11-22T11:32:53,717][WARN ][logstash.outputs.elasticsearch][main] Attempted to resurrect connection to dead ES instance, but got an error. {:url=>"https://elastic:xxxxxx@xxxxx.westeurope.azure.elastic-cloud.com:9243/", :error_type=>LogStash::Outputs::ElasticSearch::HttpClient::Pool::BadResponseCodeError, :error=>"Got response code '400' contacting Elasticsearch at URL 'https://xxxxx.westeurope.azure.elastic-cloud.com:9243/'"}

My Logstash output conf:

output {
  elasticsearch {
    hosts => ["https://****.westeurope.azure.elastic-cloud.com:9243"]
    user => "****"
    password => "****"
    index => "filebeat-7.10.0"
  }
}

The issue is, you probably mismatched Elasticsearch endpoint with Kibana endpoint. That's it.

SOLVED: The issue is, you probably mismatched Elasticsearch endpoint with Kibana endpoint . That's it.