Officially, yes. There is no built-in support for C# web builds. But there are now a few options from the community that are very stable. this one I use and works well
github.com/outfox/2dog
github.com
GitHub - outfox/2dog: 🦴 2dog is Godot in .NET
🦴 2dog is Godot in .NET. Contribute to outfox/2dog development by creating an account on GitHub.