Take care because whenyou want to give permission on a topic, you must not use "arn:aws:kafka:eu-west-1:123456789:cluster/test-cluster/9f4ea0a3-75bc-4ff9-a971-73efa2ef73c9-9/topic/test-topic2" but USE "arn:aws:kafka:eu-west-1:123456789:topic/test-cluster/9f4ea0a3-75bc-4ff9-a971-73efa2ef73c9-9/topic/test-topic2"

==> change :cluster by :topic

Reference : https://docs.aws.amazon.com/service-authorization/latest/reference/list_apachekafkaapisforamazonmskclusters.html#apachekafkaapisforamazonmskclusters-topic