Microsoft is done supporting the original Surface Duo, three years after it first launched on September 10. The company has stated from the very start that the Surface Duo would receive just three years of OS updates, meaning today is the last day that Microsoft has to stay true to its word.
Going forward, Microsoft will no longer ship new OS updates or security patches for the original Surface Duo, meaning Android 12L is the last version of the OS it will ever officially receive. Surface Duo only ever got two major OS updates, one shy of the average three that most high-end flagship Android devices get these days.
That's cool if you're into Windows, but Linux or even Lineage OS should be able to run on it.