AWS ElasticSearch Node is not configured to use the latest TLS version. Using the latest version of TLS can help keep data in-transit protected from man-in-the-middle and similar attacks.
To configure the TLS version used for an OpenSearch domain, see the AWS documentation (below). This is done via the CLI and is not available in the Console.
In Terraform -
References:
https://docs.aws.amazon.com/opensearch-service/latest/developerguide/infrastructure-security.html
https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/elasticsearch_domain#tls_security_policy