C# records default to immutability. However, struct records being a lower level construct default to mutable (which can be changed with readonly keyword):

C# records default to immutability. However, struct records being a lower level construct default to mutable (which can be changed with readonly keyword): record User(string Name, DateOnly DoB); // immutable record struct Cursor(int X, int Y); // mutable readonly record struct Point(int X, int Y); // immutable