Hello Kjetil Koldingsnes, there is no official announcement made on the availability of Grafana v12 in the Azure Managed Grafana instance. However, considering its previous release cycle and if the v12 iteration also follows the same path, then, this is likely to happen by end of 2025 or early 2026.
Please do not forget to "Accept the answer” and “up-vote” wherever the information provided helps you, this can be beneficial to other community members.