Hi @RobertTheBruce,
Welcome to the Microsoft Q&A Platform! Thank you for asking your question here.
As we understand that, AzureDB_MySQL_Flexible_Server_General_Purpose_Ddsv4Series_Compute SKU is no longer available for reservations, but a similar SKU with a slightly different name is still available. This is why you are able to see the Azure Database for MySQL Flexible Server General Purpose Ddsv4 Series Compute SKU when you try to add a new reservation.
We would like to inform you that, Azure periodically updates the SKUs that are available for reservations. It is possible that the SKU you are trying to renew is no longer available for reservations, but a similar SKU with a slightly different name is still available.
It is possible that the new SKU will work with your existing database without any issues, but it is also possible that you may need to make some changes to your database configuration in order to use the new SKU.
Please refer to the below mentioned links for more information.
https://learn.microsoft.com/en-us/azure/cost-management-billing/reservations/reservation-renew
I hope, This response will address your query and helped you to overcome on your challenges.
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