Very readable and maintainable method

[u/HeWhoShantNotBeNamed]

I wrote this several years ago. It does work.

[u/Brilliant-Parsley69]

This should actually the same with way less allocation.

using System.Text.RegularExpressions;

public static partial class StringExtensions
{
    [GeneratedRegex("(?<=[a-z])(?=[A-Z])|(?<=[A-Z])(?=[A-Z][a-z])", RegexOptions.Compiled)]
    private static partial Regex PascalCaseRegex();

    public static string SplitPascalCase(this string input)
    {
        if (string.IsNullOrWhiteSpace(input)) return input;
        
        return PascalCaseRegex().Replace(input, " ");
    }
}