It doesn't support .NET6 specifically which is what parent is asking. According to the github issue it seems that the plan is that .NET6 support will be merged after godot 4 is fully released and stabilized.

Godot ~3.2+ has support for a slightly older version of C# via Mono, I think it's the equivalent of .NET 4.8.

IIRC (and this could be wrong / have changed since I last looked into it) the idea was to re-work this in Godot 4 to provide more like bindings, so that users could opt to use Mono, .NET 6, CoreCLR, NativeAOT, or whatever version they preferred.