Last I knew, the official stance is that GDScript is not going anywhere because it offers a superior Godot development experience. That’s not to say C# is not a great programming language, but rather it is not custom tailored to Godot like GDScript. GDScript 2.0 is a big improvement under the hood and I believe, though it was over a year ago when I read this, there are plans to make it semi-compiled with JIT for speed. If/When that happens, GDScript should be as fast as JavaScript, give or take.
So, I don’t think GDScript is going to be deprecated or ignored anytime soon.