As announced in https://godotengine.org/article/godot-4-will-discontinue-visual-scripting,
Godot maintainers have agreed to discontinue the current implementation of
our VisualScript language.
The way it had been designed was not user-friendly enough and we did not
succeed in improving its usability to actually make it a good low-code
solution for users who need one.
So we prefer to remove it for Godot 4.0 and leave the door open for new,
innovative ideas around visual scripting, to be developed as plugins or
extensions now that Godot provides sufficient functionality for this
(notably via GDExtension and the godot-cpp C++ bindings).
The current module has been moved to a dedicated repository (with full Git
history extracted with `git filter-branch`):
https://github.com/godotengine/godot-visual-script
It can still be compiled as a C++ module (for now, but will likely require
work to be kept in sync with the engine repository), but our hope is that
contributors will port it to GDExtension (which is quite compatibile with
the existing C++ module code when using the godot-cpp C++ bindings).