The Next-gen General Purpose service tier for Azure SQL Managed Instance is currently in preview, and there is no specific official release date for its General Availability (GA) mentioned in the provided context.
Regarding the Flexible Memory feature, it is also currently in preview. There is no indication that it will be Generally Available at the same time as the Next-gen General Purpose tier, but it is designed to allow users to choose the memory allocation based on their workload needs.
For the most accurate and up-to-date information, it's advisable to keep an eye on official Azure announcements or documentation updates regarding these features.
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