What does "Too Many Messages without acknowledgement in topic" meaning for Quarkus consummer?

Question

I see this message in my Too Many Messages without acknowledgement in topic my-topic-retry ... amount 1 ... The connector cannot commit as a record processing has not completed.

1. Does this affect that specific topic/connector or does it affect all the topics/connectors registered in my Quarkus application? I have 3 topics configured with mp.messaging.incoming.[some-name-here].topic=some-topic-here. They are not connected to each other.
2. Can my code below somehow cause this issue?
3. How is one message not acked considered Too many (See above amount 1)?

    @Incoming("my-topic-retry")
    @Outgoing("my-topic-back")
    public Uni<Message<MyRequest>> retry(Message<MyRequest> in) {
        try {
            // Check if the message should be reprocessed immediately or delay it.
            if (delayTimeSecs == 0)
                return Uni
                    .createFrom()
                    .item(in.addMetadata(metadataOut)
                    .withPayload(in.getPayload()));
            else
                return Uni
                    .createFrom()
                    .item(in.addMetadata(metadataOut)
                    .withPayload(in.getPayload()))
                    .onItem().delayIt()
                    .by(Duration.ofSeconds(delayTimeSecs)); // Setting is 300 seconds.
        } catch(Exception ex) {
            in.nack(new IllegalStateException("An error occurred while trying to process the retry.", ex));
            return Uni.createFrom().nullItem();        
        }
    }