The focus in this release was on bringing feature parity between C# and GDScript.
When using GDScript, you can define a new node type to use in the editor by adding a global class name to your script.
Starting from Godot 4.1, this is also possible in C# by adding the [GlobalClass] attribute to your file, thanks to Raul Santos and Will Nations. You can also use the [Icon] attribute to give your global class a unique icon.
Note that as of this release projects made with C# still cannot be exported to mobile and web platforms. We are working on providing the support as soon as possible, but the resolution of this limitation will likely depend on the release of .NET 8 at the end of 2023. This means that the work on enabling mobile and web platforms can only truly start later this year."