.NET Core 3.1 was released on December 3, 2019, as a long-term release. It introduces support for C# 8.0, F# 4.7, Windows Desktop applications, single-file executable, and fast built-in JSON support.
It’s now time to bid farewell to .NET Core 3.1, since it already went out of support. This means that the .NET Core branding and Era of .NET Core (2016 -> 2022) is over. From now on, just say .NET if you want to refer to the modern .NET. Of course, you still have to say .NET Framework if you want to refer to the classic Windows-only .NET Framework.
Developers who still use .NET Core 3.1 must upgrade their projects to .NET 6.0 or later, by opening their project file, .csproj, and changing the target framework to net6.0 or later. Please note that you may have to make necessary changes to preserve the behavior of your code to make it work just like before you upgraded.
Once this is done, you’ll get benefits from the latest .NET versions, including speed improvements in .NET 7.0.
Aptivi 
Thoughts?