Amazon MQ now provides support for RabbitMQ version 3.12.13, which includes several fixes and performance improvements to the previous versions of RabbitMQ supported by Amazon MQ. Starting from RabbitMQ 3.12.13, all Classic Queues on Amazon MQ brokers are upgraded to Classic Queues version 2 (CQv2) automatically. All queues on RabbitMQ 3.12 now behave similarly to lazy queues. These changes provide a significant improvement to throughput and lower memory usage for most use cases.
Source:: Amazon AWS