When implementing IComparable<T>, you should also override Equals, <, >, <=, >=, ==, !=. (https://rules.sonarsource.com/csharp/RSPEC-1210)

Add a 'protected' constructor or the 'static' keyword to the class declaration. (https://rules.sonarsource.com/csharp/RSPEC-1118)

Remove this unused 'fdr' local variable. (https://rules.sonarsource.com/csharp/RSPEC-1481)

'Dispose' of 'writter'. (https://rules.sonarsource.com/csharp/RSPEC-2930)

'Dispose' of 'writter'. (https://rules.sonarsource.com/csharp/RSPEC-2930)

Change one instance of 'x' to a different value; comparing 'x' to itself always returns true. (https://rules.sonarsource.com/csharp/RSPEC-1764)

This async method lacks 'await' operators and will run synchronously. Consider using the 'await' operator to await non-blocking API calls, or 'await Task.Run(...)' to do CPU-bound work on a background thread.

The annotation for nullable reference types should only be used in code within a '#nullable' annotations context.

The variable 'output' is declared but never used