The rationale for the "#" syntax is that it makes it clear that the field is NOT an object property. This is an important distinction because you can do this:

  class Example {
      #myVar = 100;

      getPrivateMyVar() {
          return this.#myVar;
      }

      getLocalMyVar() {
          return this.myVar();
      }
  }

  const example = new Example();

  example.myVar = 200;

  console.log(example.getPrivateMyVar()) // 100;
  console.log(example.getLocalMyVar()) // 200;

I agree the syntax is terrible. But you need to be able to distinguish between the own object property myVar and the private field myVar.