C# is a real programming language usable outside game dev, as well as transferable to other engines or frameworks like Unity and MonoGame. GDScript is usable only in Godot.
While this is true most of the structure of the language is taken directly from Python, which depending on your interests might be a little more useful than learning C#. The only syntactical differences I’ve found so far are the additions of var, const, match, how the walrus operator is used, and of course all the nice godot editor specific keywords. The built-ins have almost exactly the same naming scheme, you can still use global functions like len on any collection, I could go on…
I would argue that someone who starts programming on gdscript today would be able to transition into Python with little to no overhead.
Maybe if someone is learning their first language that's a semi-important choice but, if you already know a programming language, syntax doesn't really have a steep learning curve.
No disrespect but judging languages on syntax is a lot like judging a book on its cover. Chosing a language is, for the experienced programmer, a choice of ecosystem, libraries, tools, architecture, and also a matter of long term maintenance, evolution, technical debts. Gscript scores very low on all of these, especially compared to the behemoth that is C#. Only unexperienced programmers and sales people use the "it looks somewhat similar so it must be" argument.
For scripting I've yet to see general purpose (with the exception of Lua) languages shine where domain specifically cannot, instead usually from my experience the general purpose language adds complexity when you don't have certain built in features or structures.
I would argue that someone who starts programming on gdscript today would be able to transition into Python with little to no overhead.