https://issues.apache.org/jira/browse/KAFKA-7077 was merged recently referring to KIP-318. Before that in AK 3.0 idempotence was enabled by default across Kafka producers.
However, some compatibility implications were missed in both cases.
If idempotence is enabled by default Connect won't be able to communicate via its producers with Kafka brokers older than version 0.11. Perhaps more importantly, for brokers older than version 2.8 the IDEMPOTENT_WRITE ACL is required to be granted to the principal of the Connect worker.
Given the above caveats, this ticket proposes to explicitly disable producer idempotence in Connect by default. This feature, as it happens today, can be enabled by setting worker and/or connector properties. However, enabling it by default should be considered in a major version upgrade and after KIP-318 is updated to mention the compatibility requirements and gets officially approved.