Naive question but why not use GDscript? I haven't had any issues with it

I'll vibe code stuff in GDscript, and I guess I more or less understand some of it.

But C# is what I've used for over a decade. C# has vastly better IDE support. It's a more complete language.

Plus a lot of C# assets/libraries don't really have GDScript counterparts.

I'll add that C# have better performances than gdscript. It doesn't make a difference for most of the things you code in a game, but it comes in handy when needed.

I'd caveat this slightly as "it depends"

For mathy stuff, 100% c# is going to be better. But if you need to round trip to the engine a lot getting stuff in and out of the dotnet heap can actually hurt performance. You also have to be _really_ careful because there are a lot of cases you generate accidental garbage (biggest one is when you use strings that are getting implicitly converted to StringNames every time you run a function, you can avoid this by pre-generating them as consts but I've run into a fair few people who never ran dotmemory or the like to see the issues).

Yes, it tooks me 2 years to see how much garbage strings conversion to String Names generates and how a fool I was calling something like Input.IsActionPressed("move_right") every frame (sadly it's the example given in the input documentation).

Yup. I remember running dotmemory on a whim and being confused by all the stringnames until I noticed what was in them. They really should put that in the docs to just make a const stringname somewhere. I use a global static class for anything I want in multiple files. But I also tend to just use statics instead of autoloads if I'm doing everything in c#.