We've just migrated from ACE 12 to ACE 13, and in our Prod env we've got some new warnings that we never saw in any of our RTL envs we migrated. Has anyone else seen this or can provide an explanation please?

Jul  4 11:12:52 serverName ACE[39191024]: IBM App Connect Enterprise v13070 (BrokerName.ExecutionGroupName) [Thread 51406] (Msg 1/1) BIP4221W: Kafka consumer 'topicName' has failed to reserve message after '10' iterations over '1' connections.

I'm getting the same BIP Message, but there is no information about it in the Knowledge Center. 
https://www.ibm.com/docs/en/app-connect/13.0.x?topic=messages-bip4000-bip4999

Is it just an informational BIP message or an error BIP message?

The last character at the end of the BIP code indicates the type, W is just a warning.

How many instances of the flow are you running?

I'm using three instances.

But I realized that the node has changed from v12 to v13:
V12

V13

The warning message disappears from the log with the configuration below:

The flow keeps the properties from the previous one, which is different from other nodes that automatically update some properties. 

IBM told us that the Kafka nodes now shares the same connection, as we only get this when there are records to consume from the Kafka Topic, we believe that the error comes from contention when records are present to consume. We consume 5 records at a time so our intention is to reduce the number of additional instances to 0 and maybe increase the batch record size if required.