Can't upgrade ECK operator


several weeks ago I deployed ECK 2.9.0 to my Azure Kubernetes, installed both CRDS and operator, deployed Elasticsearch 8.10.2 + Kibana + Logstash and all went well. Recently I decided to upgrade to ECK 2.12.1. CRDS upgrades OK, but when I try to upgrade the operator, I get this error:

The StatefulSet "elastic-operator" is invalid: spec: Forbidden: updates to statefulset spec for fields other than 'replicas', 'ordinals', 'template', 'updateStrategy', 'persistentVolumeClaimRetentionPolicy' and 'minReadySeconds' are forbidden

I made no changes to my initial deployment. Does anybody know what can be the cause of this? Thank you.