On https://go2docs.graylog.org/current/downloading_and_installing_graylog/docker_installation.htm?tocpath=Installing%20Graylog%7C_____2 it states...
"Warning: We caution you not to install or upgrade to OpenSearch 2.14! It is not supported. Doing so will break your instance!"
Therefore suggest the opensearch image should specifically be opensearchproject/opensearch:2.13.0 as opensearchproject/opensearch:2 currently points to 2.14.0 ?