Microsoft has donated the Mono Project to Wine, with WineHQ taking over as the stewards of the Mono Project upstream.
The Mono Project has been an important part of the .NET ecosystem since 2001 and Microsoft became its steward in 2016.
The last major release of the Mono Project was in July 2019, with minor patch releases until February 2024.
Microsoft recommends active Mono users and maintainers to migrate to .NET, as it has completed moving workloads to the modern fork of Mono runtime in the dotnet/runtime repository.