In my understanding, AWS is selling the service and the hosting while Grafana is selling the software. AWS is the distributore of the software and it is paying a reasonable fee to Grafana.
IF this is the case, this is a HUGE step forward for OSS.
It is a clear and simple way for OS to monetize software, while AWS keep focusing on what it does best, operations.
This ensure long term sustainability of software and hefty profit margin for the operators.
Win-Win!