Microsoft introduce a new benefit for customers with Windows Server Datacenter licences with SA purchased through an Enterprise Agreement. It’s an extension to the Azure Hybrid Benefit and waives the fees for the Azure Stack HCI host service and Windows Server guest subscriptions, as long as all physical cores of the Azure Stack HCI cluster are licensed with Windows Server Datacenter Core licences.

You can find the announcement article here: https://bit.ly/3S4ldHf, and this is a good place to find out more, such as how the benefit is activated: https://bit.ly/3yOX54F.