Make ECK IPv6 compatible #3654 (issues: #2830, #3649) - in an accompanying change network.publish_host setting value was switched to DNS name. This might result in non-ready Pods being included in the headless service for Elasticsearch StatefulSets.
Enforce a strict upgrade order between stack components #3537 (issues: #2600, #3535) - ECK will prevent updates that would violate Elastic Stack upgrade process version constraints. ECK 1.3.0 won’t apply any updates to resources that are in violation of those constraints until versions are updated to (at least) the same minors.
Add set-default-security-context flag to handle runAs user in ES 8.0+ #3342 (issue: #2791) - a default security context is added to Elasticsearch 8.0+ Pods in order to deal with volume filesystem permissions. Can be disabled through operator configuration on environments with restricted security settings (Openshift, for example).
Allow init containers modifications #3336 (issue: #2306) - modifications to built-in init containers will be merged with the defaults instead of completely replacing them.