A question is: is it a problem that C# uses a static method for this?

If I have a static class, with static methods, is that enough, or would I prefer to have functions declared stand-alone within a namespace?

In other words does public static class equal module with static methods 'exports'.
The problem for me is that then opens the rabbithole of do I want to delcare variables with a module level scope along with these? Now C# can do that with a static field within the same static class.